#11 TLE 求助

#include<bits/stdc++.h>
#define int long long
#define endl '\n'
#define ls (now<<1)
#define rs (now<<1|1)
#define P pair<int,int>
#define pb() push_back()
using namespace std;
const int N=2e5+10;
int n,Q,a[N],b[N];
struct qu{
	int l,r,num;
}q[N];
int len;		int t[N]={};
int bl[N],br[N],belong[N],ansl[N];
bool cmp(qu a,qu b){
	return belong[a.l]==belong[b.l] ? a.r<b.r : a.l<b.l;
}
vector<qu>ques[N];
signed main(){
	ios::sync_with_stdio(0);
	cin.tie(0),cout.tie(0);
	cin>>n>>Q;
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	len=pow(n,0.333);
	int num=(n+len-1)/len;
	for(int i=1;i<=num;i++){
		bl[i]=br[i-1]+1;
		br[i]=min(n,i*len);
	}
	br[num]=n;
	for(int i=1;i<=num;i++){
		for(int j=bl[i];j<=br[i];j++){
			belong[j]=i;
		}
	}
	for(int i=1;i<=Q;i++){
		cin>>q[i].l>>q[i].r;
		q[i].num=i;
		
	}
	sort(q+1,q+Q+1,cmp);
	
	for (int i=1;i<=Q;i++)ques[belong[q[i].l]].push_back(q[i]);
	
	int lnow,rnow;
	
	for(int i=1;i<=num;i++){
		lnow=br[i]+1;
		rnow=br[i];
		int ans=0,lastans=0;
		memset(t,0,sizeof t);
		for (auto it : ques[i]){
			if(belong[it.l]==belong[it.r]){//暴力搞
				int t1[N]={};
				for(int j=it.l;j<=it.r;j++){
					t1[a[j]]++;
					
				}
				for(int i=0;i<=N;i++){
					if(t1[i]==0){
						ans=i;
						break;
					}
				}
				ansl[it.num]=ans;
				ans=lastans=0;
			}else{
				ans=lastans;//重置
				while(lnow<br[i]+1){
					t[a[lnow]]--;
					lnow++;
				}
				while(rnow<it.r){//先移动右端点
					rnow++;
					t[a[rnow]]++;
					if(t[a[rnow]]==1 and ans==a[rnow]){
						while(t[ans]!=0 and ans<=N){ans++;lastans++;}
					}
				}
				while(lnow>it.l){//再改左端点
					lnow--;
					t[a[lnow]]++;
					if(t[a[lnow]]==1 and ans==a[lnow]){
						while(t[ans]!=0 and ans<=N){ans++;}
					}
				}
				ansl[it.num]=ans;
			}
		}
	}
	for(int i=1;i<=Q;i++)cout<<ansl[i]<<"\n";
	return 0;
}