#include <stdio.h>
#include <map>

using namespace std;

int main() {
	while (1) {
		int m, q, i, j;
		scanf("%d %d", &m, &q);
		
		if (m == 0 && q == 0) {
			break;
		}
		
		int ids[m];
		int nexts[m];
		map<int, int> lasts;
		
		for (i = 0; i < m; ++i) {
			scanf("%d", ids + i);
			int &id = lasts[ids[i]];
			nexts[i] = 0;	// This should be unnecessary!!!
			if (id)
				nexts[id - 1] = i;
			id = i + 1;
		}
		for (i = 0; i < q; ++i) {
			int start, end;
			scanf("%d %d", &start, &end);
			if (start == end) {
				printf("OK");
				goto nazdar;
			}
			--start;
			--end;
			for (j = start; j <= end; ++j) {
				if (nexts[j] && nexts[j] <= end) {
					printf("%d", ids[j]);
					goto nazdar;
				}
			}
			printf("OK");
		nazdar:
			putchar('\n');
		}
		putchar('\n');
	}
	return 0;
}