#include <cstdio>
#include <cstring>
#include <algorithm>
#include <stack>
#include <vector>

using namespace std;

#define REP(i,n) for(int i=0; i<n; ++i)
#define PB push_back

int a[1000010];
int prev[1000010];
typedef pair<int,int> pii;
pii p[1000010];

int tab[2100000];
int old[1000010];

int p2;
int wynik;

bool ok(int b, int e){
	int oldB = b;
	if(b == e) return true;
	b += p2;
	e += p2;
	int worst = tab[e];
	while(b+1 < e){
		if(b%2 == 0) worst = max(worst, tab[b+1]);
		if(e%2 == 1) worst = max(worst, tab[e-1]);
		b >>= 1;
		e >>= 1;
	}
	if(worst >= 0) wynik = old[worst];
	return worst < oldB;
}

int main()
{
	while(true){
		int n, q;
		scanf("%d%d", &n, &q);
		if(n == 0 && q == 0) break;
		REP(i,n) scanf("%d", &a[i]), p[i] = pii(a[i],i);
		sort(p, p+n);
		int wsk = 0;
		REP(i,n) old[i] = a[i];
		
		a[p[0].second] = 0;
		for(int i=1; i<n; ++i){
			if(p[i].first != p[i-1].first) wsk++;
			a[p[i].second] = wsk;
		}
		
		p2 = 1;
		while(p2 <= n) p2 <<= 1;
		
		REP(i,wsk+1) prev[i] = -1;
		REP(i,n){
			int val = a[i];
			tab[p2 + i] = prev[val];
			prev[val] = i;
		}
		for(int i=p2-1; i>0; --i) tab[i] = max(tab[i<<1], tab[(i<<1) + 1]);
		
		while(q--){
			int b, e;
			scanf("%d%d", &b, &e);
			b--; e--;
			if(ok(b,e)) printf("OK\n"); else printf("%d\n", wynik);
		}
		printf("\n");
	}
	return 0;
}