#include<bits/stdc++.h>
using namespace std;
#define ONLINE_JUDGE
namespace Fread
{
	const int SIZE = 1 << 16;
	char buf[SIZE], *S, *T;
	inline char getchar() { if (S == T) { T = (S = buf) + fread(buf, 1, SIZE, stdin); if (S == T) return '\n'; } return *S++; }
}
using namespace Fread;
namespace Fwrite
{
	const int SIZE = 1 << 16;
	char buf[SIZE], *S = buf, *T = buf + SIZE;
	inline void flush() { fwrite(buf, 1, S - buf, stdout); S = buf; }
	inline void putchar(char c) { *S++ = c; if (S == T) flush(); }
	struct NTR { ~NTR() { flush(); } } ztr;
}
using namespace Fwrite;
#define getchar Fread::getchar
#define putchar Fwrite::putchar
namespace Fastio
{
	struct Reader
	{
		template <typename T> Reader& operator >> (T &x)
		{
			x = 0;
			short f = 1;
			char c = getchar();
			while (c < '0' || c > '9') { if (c == '-') f *= -1; c = getchar(); }
			while (c >= '0' && c <= '9') x = (x << 3) + (x << 1) + (c ^ 48), c = getchar();
			x *= f;
			return *this;
		}
		Reader& operator >> (double &x)
		{
			x = 0;
			double t = 0;
			short f = 1, s = 0;
			char c = getchar();
			while ((c < '0' || c > '9') && c != '.') { if (c == '-') f *= -1; c = getchar(); }
			while (c >= '0' && c <= '9' && c != '.') x = x * 10 + (c ^ 48), c = getchar();
			if (c == '.') c = getchar();
			else { x *= f; return *this; }
			while (c >= '0' && c <= '9') t = t * 10 + (c ^ 48), s++, c = getchar();
			while (s--) t /= 10.0;
			x = (x + t) * f;
			return *this;
		}
		Reader& operator >> (long double &x)
		{
			x = 0;
			long double t = 0;
			short f = 1, s = 0;
			char c = getchar();
			while ((c < '0' || c > '9') && c != '.') { if (c == '-') f *= -1; c = getchar(); }
			while (c >= '0' && c <= '9' && c != '.') x = x * 10 + (c ^ 48), c = getchar();
			if (c == '.') c = getchar();
			else { x *= f; return *this; }
			while (c >= '0' && c <= '9') t = t * 10 + (c ^ 48), s++, c = getchar();
			while (s--) t /= 10.0;
			x = (x + t) * f;
			return *this;
		}
		Reader& operator >> (__float128 &x)
		{
			x = 0;
			__float128 t = 0;
			short f = 1, s = 0;
			char c = getchar();
			while ((c < '0' || c > '9') && c != '.') { if (c == '-') f *= -1; c = getchar(); }
			while (c >= '0' && c <= '9' && c != '.') x = x * 10 + (c ^ 48), c = getchar();
			if (c == '.') c = getchar();
			else { x *= f; return *this; }
			while (c >= '0' && c <= '9') t = t * 10 + (c ^ 48), s++, c = getchar();
			while (s--) t /= 10.0;
			x = (x + t) * f;
			return *this;
		}
		Reader& operator >> (char &c)
		{
			c = getchar();
			while (c == ' ' || c == '\n' || c == '\r') c = getchar();
			return *this;
		}
		Reader& operator >> (char *str)
		{
			int len = 0;
			char c = getchar();
			while (c == ' ' || c == '\n' || c == '\r') c = getchar();
			while (c != ' ' && c != '\n' && c != '\r') str[len++] = c, c = getchar();
			str[len] = '\0';
			return *this;
		}
		Reader& operator >> (string &str)
		{
			str.clear();
			char c = getchar();
			while (c == ' ' || c == '\n' || c == '\r') c = getchar();
			while (c != ' ' && c != '\n' && c != '\r') str.push_back(c), c = getchar();
			return *this;
		}
		Reader() {}
	} cin;
	const char endl = '\n';
	struct Writer
	{
		const int Setprecision = 6;
		typedef int mxdouble;
		template <typename T> Writer& operator << (T x)
		{
			if (x == 0) { putchar('0'); return *this; }
			if (x < 0) putchar('-'), x = -x;
			static short sta[40];
			short top = 0;
			while (x > 0) sta[++top] = x % 10, x /= 10;
			while (top > 0) putchar(sta[top] + '0'), top--;
			return *this;
		}
		Writer& operator << (double x)
		{
			if (x < 0) putchar('-'), x = -x;
			mxdouble _ = x;
			x -= (double)_;
			static short sta[40];
			short top = 0;
			while (_ > 0) sta[++top] = _ % 10, _ /= 10;
			if (top == 0) putchar('0');
			while (top > 0) putchar(sta[top] + '0'), top--;
			putchar('.');
			for (int i = 0; i < Setprecision; i++) x *= 10;
			_ = x;
			while (_ > 0) sta[++top] = _ % 10, _ /= 10;
			for (int i = 0; i < Setprecision - top; i++) putchar('0');
			while (top > 0) putchar(sta[top] + '0'), top--;
			return *this;
		}
		Writer& operator << (long double x)
		{
			if (x < 0) putchar('-'), x = -x;
			mxdouble _ = x;
			x -= (long double)_;
			static short sta[40];
			short top = 0;
			while (_ > 0) sta[++top] = _ % 10, _ /= 10;
			if (top == 0) putchar('0');
			while (top > 0) putchar(sta[top] + '0'), top--;
			putchar('.');
			for (int i = 0; i < Setprecision; i++) x *= 10;
			_ = x;
			while (_ > 0) sta[++top] = _ % 10, _ /= 10;
			for (int i = 0; i < Setprecision - top; i++) putchar('0');
			while (top > 0) putchar(sta[top] + '0'), top--;
			return *this;
		}
		Writer& operator << (__float128 x)
		{
			if (x < 0) putchar('-'), x = -x;
			mxdouble _ = x;
			x -= (__float128)_;
			static short sta[40];
			short top = 0;
			while (_ > 0) sta[++top] = _ % 10, _ /= 10;
			if (top == 0) putchar('0');
			while (top > 0) putchar(sta[top] + '0'), top--;
			putchar('.');
			for (int i = 0; i < Setprecision; i++) x *= 10;
			_ = x;
			while (_ > 0) sta[++top] = _ % 10, _ /= 10;
			for (int i = 0; i < Setprecision - top; i++) putchar('0');
			while (top > 0) putchar(sta[top] + '0'), top--;
			return *this;
		}
		Writer& operator << (char c) { putchar(c); return *this; }
		Writer& operator << (char *str)
		{
			int cur = 0;
			while (str[cur]) putchar(str[cur++]);
			return *this;
		}
		Writer& operator << (const char *str)
		{
			int cur = 0;
			while (str[cur]) putchar(str[cur++]);
			return *this;
		}
		Writer& operator << (string str)
		{
			int st = 0, ed = str.size();
			while (st < ed) putchar(str[st++]);
			return *this;
		}
		Writer() {}
	} cout;
}
using namespace Fastio;
#define cin Fastio::cin
#define cout Fastio::cout
#define endl Fastio::endl
const int N=2e5+5;
int mp[N],n,m,a[N],ans[N],mpp[N];
struct nd{
	int l,r,id;
}c[N];
int pos[N];
set<int> s;
const int len=725;
bool cmp(nd x,nd y){
	if(pos[x.l]==pos[y.l]) {
		if(pos[x.l]&1) return x.r>y.r;
		else return x.r<y.r;
	}
	return pos[x.l]<pos[y.l];
}
int main(){
	cin>>n>>m;for(int i=1;i<=n;i++) cin>>a[i];
	for(int i=1;i<=m;i++) {
		c[i].id=i;
		cin>>c[i].l>>c[i].r;
	}
	for(int i=1;i<=n;i++) pos[i]=i/len+(i%len!=0),mpp[a[i]]++;
	int maxx=0;
	for(int i=0;i<=n;i++){
		s.insert(i);
		if(mpp[i]==0){
			maxx=i;
			break;
		}
	}
	sort(c+1,c+1+m,cmp);
	int l=c[1].l,r=c[1].r;
	for(int i=l;i<=r;i++){
		mp[a[i]]++;
		if(mp[a[i]]==1) if(a[i]<=maxx) s.erase(a[i]);
	}
	ans[c[1].id]=*s.begin();
	for(int i=2;i<=m;i++){
		while(l>c[i].l){
			l--;
			mp[a[l]]++;
			if(mp[a[l]]==1) if(a[l]<=maxx) s.erase(a[l]);
		}
		while(r<c[i].r){
			r++;
			mp[a[r]]++;
			if(mp[a[r]]==1) if(a[r]<=maxx) s.erase(a[r]);
		}
		while(l<c[i].l){
			mp[a[l]]--;
			if(mp[a[l]]==0) if(a[l]<=maxx) s.insert(a[l]);
			l++;
		}
		while(r>c[i].r){
			mp[a[r]]--;
			if(mp[a[r]]==0) if(a[r]<=maxx) s.insert(a[r]);
			r--;
		}
		ans[c[i].id]=*s.begin();
	}
	for(int i=1;i<=m;i++) cout<<ans[i]<<"\n";
	return 0;
}