#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>using namespace std;#define maxn 200005struct TreeNodeType {    int l,r,dis,mid,flag;        bool if_;};struct TreeNodeType tree[maxn<<2];struct QueryType {    int l,r,id;};struct QueryType qu[maxn];int n,m,ai[maxn],sg[maxn],ans[maxn],Next[maxn],last[maxn];int num[maxn];inline void in(int &now){    char Cget=getchar();now=0;    while(Cget>‘9‘||Cget<‘0‘) Cget=getchar();    while(Cget>=‘0‘&&Cget<=‘9‘)    {        now=now*10+Cget-‘0‘;        Cget=getchar();    }}void tree_build(int now,int l,int r){    tree[now].l=l,tree[now].r=r;    if(l==r) { tree[now].dis=sg[l];return; }    tree[now].mid=l+r>>1;    tree_build(now<<1,l,tree[now].mid);    tree_build(now<<1|1,tree[now].mid+1,r);    tree[now].dis=min(tree[now<<1].dis,tree[now<<1|1].dis);}void tree_down(int now){    tree[now<<1].dis=min(tree[now<<1].dis,tree[now].flag);    tree[now<<1|1].dis=min(tree[now<<1|1].dis,tree[now].flag);    if(tree[now<<1].if_) tree[now<<1].flag=min(tree[now<<1].flag,tree[now].flag);    else tree[now<<1].flag=tree[now].flag,tree[now<<1].if_=true;    if(tree[now<<1|1].if_) tree[now<<1|1].flag=min(tree[now<<1|1].flag,tree[now].flag);    else tree[now<<1|1].flag=tree[now].flag,tree[now<<1|1].if_=true;    tree[now].if_=false;return ;}void tree_change(int now,int l,int r,int x){    if(tree[now].l==l&&tree[now].r==r)    {        tree[now].dis=min(tree[now].dis,x);        if(tree[now].if_) tree[now].flag=min(tree[now].flag,x);        else tree[now].flag=x,tree[now].if_=true;        return ;    }    if(tree[now].if_) tree_down(now);    if(r<=tree[now].mid) tree_change(now<<1,l,r,x);    else if(l>tree[now].mid) tree_change(now<<1|1,l,r,x);    else tree_change(now<<1,l,tree[now].mid,x),tree_change(now<<1|1,tree[now].mid+1,r,x);    tree[now].dis=min(tree[now<<1].dis,tree[now<<1|1].dis);}int tree_query(int now,int to){    if(tree[now].l==tree[now].r) return tree[now].dis;    if(tree[now].if_) tree_down(now);    if(to<=tree[now].mid) return tree_query(now<<1,to);    else return tree_query(now<<1|1,to);}bool cmp(QueryType aa,QueryType bb){    return aa.l<bb.l;}int main(){    freopen("mex.in","r",stdin);    freopen("mex.out","w",stdout);    in(n),in(m);int now=0;    for(int i=1;i<=n;i++) in(ai[i]);    for(int i=1;i<=n;i++)    {        num[ai[i]]++;        while(num[now]) now++;        sg[i]=now;        if(last[ai[i]]) Next[last[ai[i]]]=i;        last[ai[i]]=i;    }    sg[n+1]=now;tree_build(1,1,n);    for(int i=1;i<=n;i++) if(!Next[i]) Next[i]=n+1;    for(int i=1;i<=m;i++) in(qu[i].l),in(qu[i].r),qu[i].id=i;    sort(qu+1,qu+m+1,cmp),now=1;    for(int no=1;no<=m;no++)    {        while(now<qu[no].l) tree_change(1,now,Next[now]-1,ai[now]),now++;        ans[qu[no].id]=tree_query(1,qu[no].r);    }    for(int i=1;i<=m;i++) printf("%d\n",ans[i]);    return 0;}