#include <cstdio>
#include <vector>
#include <map>

using namespace std;

const int MMAX = 1000001;
const int INF = 2147000000;

int main()
{
	vector<int> v;
	vector<int> bad_pos;
	map<int, int> pos_map;

	int M, Q;
	while (1)
	{
		scanf("%d%d", &M, &Q);
		if (M == 0 && Q == 0)
			break;

		v.resize(M+1);
		bad_pos.resize(M+1);
		for (int i = 0; i <= M; ++i)
			bad_pos[i] = INF;
		for (int i = 1; i <= M; ++i)
		{
			int key;
			scanf("%d", &key);
			v[i] = key;
			if (pos_map.count(key) > 0)
			{
				int prev_pos = pos_map[key];
				bad_pos[prev_pos] = i;
			}
			pos_map[key] = i;
		}

		int last = INF;
		for (int i = M; i > 0; --i)
			if (bad_pos[i] > last)
				bad_pos[i] = last;
			else
				last = bad_pos[i];

		for (int i = 0; i < Q; ++i)
		{
			int f, l;
			scanf("%d%d", &f, &l);
			if (bad_pos[f] > l)
				printf("OK\n");
			else
				printf("%d\n", v[bad_pos[f]]);
		}

	}
	return 0;
}