#include<bits/stdc++.h> 
using namespace std;
const int N = 5e4 + 9,SqrtN = 259,M = 5e4 + 9,INF = 0x3f3f3f3f;
int n,m;
int a[N],a2[N],top;

int block_len,block_cnt;
struct block{
	int l,r;
} b[N];
int belong[N];
void build_block(){
	block_len = block_cnt = sqrt(n);
	for(int i = 1;i <= block_cnt;i++){
		b[i].l = b[i - 1].r + 1;
		b[i].r = b[i].l + block_len - 1;
	}
	b[block_cnt].r = n;
    for(int i = 1;i <= block_cnt;i++)
        for(int j = b[i].l;j <= b[i].r;j++)
            belong[j] = i;
}
struct Query{
	int l,r;
	int id;
} q[M];
bool cmp(Query q1,Query q2){
	return (belong[q1.l] ^ belong[q2.l]) ? belong[q1.l] < belong[q2.l] : q1.r < q2.r;
}
struct rec{
	int first[N],last[N];
	int ans;
	void clear(){
		for(int i = 1;i <= top;i++){
			first[i] = INF;
			last[i] = -INF;
		}
		ans = 0;
	}
} tmp[4];
int ans[M];

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	cin >> n >> m;
	build_block();
	for(int i = 1;i <= n;i++){
		cin >> a[i];
		a[i] += a[i - 1];
	}
	for(int i = 1;i <= n;i++)
		a2[++top] = a[i];
	a2[++top] = a[0];
	sort(a2 + 1,a2 + top + 1);
	top = unique(a2 + 1,a2 + top + 1) - a2 - 1;
	for(int i = 0;i <= n;i++)
		a[i] = lower_bound(a2 + 1,a2 + top + 1,a[i]) - a2;
	for(int i = 1;i <= m;i++){
		cin >> q[i].l >> q[i].r;
		q[i].l--;
		q[i].id = i;
	}
	sort(q + 1,q + m + 1,cmp);
	int lres = -1,rres = -1;
	bool f = true;//上次是否是块内暴力
	tmp[1].clear();tmp[2].clear();
	for(int i = 1;i <= m;i++){
        int L = q[i].l,R = q[i].r;
        int pos_l = belong[L],pos_r = belong[R];
        if(pos_r - pos_l <= 1){
        	for(int j = L;j <= R;j++)
        		if(tmp[2].first[a[j]] == INF)
        			tmp[2].first[a[j]] = j;
        	for(int j = R;j >= L;j--)
        		if(tmp[2].last[a[j]] == -INF){
        			tmp[2].last[a[j]] = j;
        			tmp[2].ans = max(tmp[2].ans,tmp[2].last[a[j]] - tmp[2].first[a[j]]);
				}
        	lres = L;rres = R;
        	ans[q[i].id] = tmp[2].ans;
        	f = true;
        	for(int j = L;j <= R;j++){
        		tmp[2].first[a[j]] = INF;
        		tmp[2].last[a[j]] = -INF;
			}
			tmp[2].ans = 0;
        	continue;
		}
        if((pos_l ^ belong[lres]) || f){
        	tmp[1].clear();
        	for(int j = b[pos_l + 1].l;j <= R;j++)
        		if(tmp[1].first[a[j]] == INF)
        			tmp[1].first[a[j]] = j;
        	for(int j = R;j >= b[pos_l + 1].l;j--)
        		if(tmp[1].last[a[j]] == -INF){
        			tmp[1].last[a[j]] = j;
        			tmp[1].ans = max(tmp[1].ans,tmp[1].last[a[j]] - tmp[1].first[a[j]]);
				}
        	rres = R;
			tmp[0].ans = tmp[1].ans;
        	lres = b[pos_l + 1].l;
        	while(lres > L){
				lres--;
				tmp[1].ans = max(tmp[1].ans,tmp[1].last[a[lres]] - lres);
			}
			ans[q[i].id] = tmp[1].ans;
			tmp[1].ans = tmp[0].ans;
			f = false;
        	continue;
		}
        while(rres < R){
        	rres++;
			tmp[1].last[a[rres]] = rres;
			tmp[1].ans = max(tmp[1].ans,rres - tmp[1].first[a[rres]]);
		}
        tmp[0].ans = tmp[1].ans;
        lres = b[pos_l + 1].l;
        while(lres > L){
			lres--;
			tmp[1].ans = max(tmp[1].ans,tmp[1].last[a[lres]] - lres);
		}
    	ans[q[i].id] = tmp[1].ans;
		tmp[1].ans = tmp[0].ans;
    	f = false;
	}
	for(int i = 1;i <= m;i++)
		cout << ans[i] << '\n';
	return 0;
}