#include <string>
#include <string.h>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <algorithm>
#include <list>
#include <set>
#include <map>
#include <iostream>
using namespace std;
#define DEBUG 0
#define III if(DEBUG >1)
#define VVV if(DEBUG)

#define MX 2000000

int M, Q;
long long kluce[MX];

void vypis() { 
  for (int i=0; i<M; i++)
   cout << kluce[i]<< "  ";
	cout <<"\n";
}

int main() {
  while (1) {
		cin >> M >> Q;
		III cout <<M<<Q<<"\n";

		if (!M && !Q) return 0;

		for (int  i = 0; i < M; i++)
			cin >> kluce[i];
		III vypis();
		int from, to;
		for (int i = 0; i < Q; i++) {
			cin >> from >> to;
			
			set<long long> a;
			bool uzje = false;
			for (int j = from-1; j < to; j++) {
				if (a.count( kluce[j] ) ) {
					cout << kluce[j] << "\n";
					uzje = true;
					break;
				} else {
					a.insert( kluce[j]);
				}
			}
			
			if (!uzje) cout << "OK\n";
		}
		cout << "\n";
  }
  return 0;
}