#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 1
#define III if(DEBUG >1)
#define VVV if(DEBUG)

#define MX 2000000
//#define 

int M, Q;
int kluce[MX];
int predc[MX];
map<int, int> mpp;


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";
		mpp.clear();
		if (!M && !Q)
			return 0;
		int ttt;
		for (int  i = 0; i < M; i++) {
			scanf("%d", & ttt );
			kluce[i] =ttt;
			if (mpp.count(ttt)) {
				predc[i] =mpp[ttt];
			}	else {
				predc[i] =-1;
			}
			mpp[ttt] =i;
		}
		/*for (int  i = 0; i < M; i++) {
			cout << predc[i]<< " ";
			}
		cout << "\n";*/
		III vypis();
		int from, to;
		for (int i = 0; i < Q; i++) {
			scanf("%d %d", &from, &to);
			bool uzje = false;

			if (! (to - from)) {
				cout << "OK\n";
				continue;
			}
			for (int j = to-1; j >=from-1; j--) {
				
				if (predc[j] <from-1) {///check -1 !!!!
					//cout << predc[j] << "\n";
					continue;
				}
				cout <<kluce[j]<<"\n";
				uzje =1;
				break;
			}
			if (!uzje) cout << "OK\n";
		}
		cout << "\n";
  }
  return 0;
}