#include <iostream>
#include <cstdio>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <cmath>
#include <algorithm>
using namespace std;
#define REP(i,a,b) for (int i = (a); i <= (b); ++i)
#define FORI(i,n) REP(i,1,n)
#define FOR(i,n) REP(i,0,int(n)-1)
#define mp make_pair
#define pb push_back
#define pii pair<int,int>
#define vi vector<int>
#define ll long long
#define SZ(x) ((int)(x.size()))
#define IN(x,y) ((y).find((x)) != (y).end())
#define DBG(v) cerr << #v << " = " << (v) << endl;
#define FOREACH(i,t) for (typeof (t.begin()) i = t.begin(); i != t.end(); i++)
#define fi first
#define se second

#define maxn 1000100
#define M (1<<21)

int n,q;
int next[maxn], k[maxn];
int T[maxn];
int W[2*M+17];
pair<int,int> tt[maxn];

void add(int pos, int val)
{
	int start = pos;
	T[start] = val;
	pos += M;
	while(pos > 1)
	{
		if(T[W[pos]] > val)
			W[pos] = start;
		pos >>= 1;
	}
}

int getmin(int a, int b)
{
	a += M;
	b += M;
	int res = W[a];
	while(a+1 < b)
	{
		if(a%2 == 0) if(T[res] > T[W[a+1]])
			res = W[a+1];
		if(b%2 == 1) if(T[res] > T[W[b-1]])
			res = W[b-1];
		a >>= 1;
		b >>= 1;
	}
	return res;
}

int main ()
{
	while(1)
	{
		scanf("%d%d", &n, &q);
		if(!n) return 0;
		FOR(i,n) scanf("%d", &k[i]);
		FOR(i,n) tt[i] = mp(k[i], i);
		sort(tt,tt+n);
		FOR(i,n)
		{
			if(i+1 < n && tt[i+1].fi == tt[i].fi)
				next[tt[i].se] = tt[i+1].se;
			else
				next[tt[i].se] = n+7;
		}
		FOR(i,2*M) W[i] = n+8;
		T[n+8] = n+10;
		//FOR(i,n) printf("next[%d] = %d\n", i, next[i]);
		FOR(i,n) add(i, next[i]);
		FOR(i,q)
		{
			int a,b;
			scanf("%d%d", &a, &b);
			int mx = getmin(a-1,b);
			//printf("mx = %d\n", mx);
			if(T[mx] < b) printf("%d\n", k[mx]);
			else printf("OK\n");
		}
		printf("\n");
	}
	return 0;
}