#include <stdio.h>
#include <memory.h>
#include <malloc.h>
#include <stdlib.h>
#define size (10000000)
#define hash(x) (((x)*19u+13)%(size))
#define uint unsigned int

struct ww {
	uint num;
	uint pos;
};

int main() {
	ww *set = (ww*)malloc( size * sizeof( ww ) );
	ww *end = set;

	uint *key = (uint*)malloc( size * sizeof( uint ) );
	uint *jmp = (uint*)malloc( size * sizeof( uint ) );

	end += size - 1;
	if( !set || !key ) {
		printf("mem");
		return 1;
	};
	for( ;; ) {
		uint ks, qs, f, t;
		scanf( "%u %u", &ks, &qs );
		if( !ks && !qs ) return 0;
		for( uint i = 0; i < ks; i++ ) {
			scanf( "%u", &key[i] );
		}
		
		memset( set, 0, size * sizeof( ww ) );
		memset( jmp, 0, size * sizeof( uint ) );
		for( uint i = 0; i < ks; i++ ) {
			uint n = key[i];
			ww *s = set + hash( hash( n ) );
			ww *start = s;
			while( s->num ) {				
				if( s->num == n ) {
					jmp[ s->pos ] = i;
					break;
				}
				s++;
				if( s == start ) return 1;
				if( s > end ) s = set;
			}
			s->num = n;
			s->pos = i;
		}

		for( uint j = 0; j < qs; j++ ) {
			scanf( "%u %u", &f, &t );
			t--;
			for( uint i = f - 1; i < t; i++ ) {
				if( jmp[i] && jmp[ i ] <= t ) {
					printf( "%d\n", key[i] );
					goto skip;
				}
			}
			printf("OK\n");
			skip: ;
		}
		printf("\n");
	}
}