样例和自己手造的几组数据都能过，但是提交就全WA

求万能的谷民能给一份数据规模较小的HACK数据 orz

代码如下：：

#include <bits/stdc++.h>
using namespace std;
const int maxn=2e6+5;
struct node{
	int l,r,id;
	inline bool operator < (node tmp) const{
		return r<tmp.r;
	}
}q[maxn];
int n,m,t,a[maxn],c[maxn],pos1[maxn],pos2[maxn],ans[maxn];
inline int lowbit(int x) {return x&-x; }
inline void update(int x,int dat) {for (int i=x;i<=n;i+=lowbit(i)) c[i]+=dat; }
inline int query(int x){
	int res=0;
	for (int i=x;i;i-=lowbit(i)) res+=c[i];
	return res;
}
int main(){
	scanf("%d%d%d",&n,&t,&m);
	for (int i=1;i<=n;i++) scanf("%d",&a[i]);
	for (int i=1;i<=m;i++){
		scanf("%d%d",&q[i].l,&q[i].r);
		q[i].id=i;
	}
	sort(q+1,q+m+1);
	for (int i=1,p=0;i<=m;i++){
		while (p<q[i].r){
			p++;
			if (pos1[a[p]] && pos2[a[p]]){
				update(pos1[a[p]],-1);
				update(p,1);
				pos1[a[p]]=pos2[a[p]];
				pos2[a[p]]=p;
			}else if (!pos1[a[p]] && pos2[a[p]]){
				update(pos2[a[p]],1);
				update(p,1);
				pos1[a[p]]=pos2[a[p]];
				pos2[a[p]]=p;
			}else pos2[a[p]]=p;
		}
		ans[q[i].id]=(query(q[i].r)-2*query(q[i].l-1))/2;
	}
	for (int i=1;i<=m;i++) printf("%d\n",ans[i]);
	return 0;
}