#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];
map<int, set<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";

		if (!M && !Q) return 0;
		int ttt;
		for (int  i = 0; i < M; i++) {
			scanf("%d", & ttt );
			kluce[i] =ttt;
			mpp[ttt].insert(i);
		}
		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 = from-1; j < to; j++) {
				set<int>::iterator it =mpp[ kluce[j] ].find(j);
				it++;
				if (it ==mpp[ kluce[j] ].end())
					continue;
				if ( (*it) < to) { //< alebo <= ???
					cout <<kluce[j]<<"\n";
					uzje =1;
					break;
				}
			}
			if (!uzje) cout << "OK\n";
		}
		cout << "\n";
  }
  return 0;
}