#include <stdio.h>
#include <stdlib.h>

static int hol[1024000], v[1024000], r[1024000][2], t[1024000], h[1024000], s[1024000];

int cmp(const void *a_, const void *b_)
{
	const int *a = a_, *b = b_;
	if (a[0] != b[0]) return a[0]-b[0];
	return a[1]-b[1];
}

int main(void)
{
	int first = 1;
	for (;;) {
		int m, q, i, j;
		scanf("%d %d", &m, &q);
		if (m == 0) return 0;
		if (first) first = 0;
		else putchar('\n');
		for (i = 0; i < m; i++) {
			scanf("%d", &r[i][0]);
			v[i] = r[i][0];
			r[i][1] = i;
		}
		qsort(r, m, 2*sizeof(int), cmp);
		for (i = 0; i < m; i++) {
			hol[r[i][1]] = i;
		}
		for (i = 0; i < m; i++) {
			int x = hol[i]-1;
			if (r[x][0] == r[hol[i]][0]) t[i] = r[x][1];
			else t[i] = -1;
		}
		h[0] = -1;
		for (i = 1; i < m; i++) {
			if (t[i] > h[i-1]) {
				h[i] = t[i];
				s[i] = v[i];
			} else {
				h[i] = h[i-1];
				s[i] = s[i-1];
			}
		}
		for (i = 0; i < q; i++) {
			int a, b;
			scanf("%d %d", &a, &b);
			a--; b--;
			if (a <= h[b]) printf("%d\n", s[b]);
			else printf("OK\n");
		}
	}
}