// 
// File:   unique.cc
// Author: cteam18
//
// Created on November 13, 2011, 9:12 AM
//

#include <stdlib.h>
#include <stdio.h>
#include <vector>
#include <utility>
#include <algorithm>


using namespace std;

typedef pair<int, int> pii;
typedef vector<pii>::iterator itvp;

#define all(c) (c).begin(), (c).end()



int main(int argc, char** argv) {
    long m, q;
    vector<int> keys, from, types;
    vector<pii> keyssort;
    scanf("%d%d", &m, &q);
    while(m || q){
        int beg = -1;
        int type;
        keys = from = types = vector<int>(m);
        keyssort = vector<pii>(m);
        for(int i = 0; i < m; ++i){
            scanf("%d", &(keys[i]));
            keyssort[i] = pii(keys[i], i);
        }
        sort(all(keyssort));
        for(int i = 0; i < m; ++i){
            itvp iter = lower_bound(all(keyssort), pii(keys[i], i));
            if(iter != keyssort.begin() && (--iter)->first == keys[i] && iter->second > beg){
                beg = iter->second;
                type = keys[i];
            }
            from[i] = beg;
            types[i] = type;
            
        }
        for(int i = 0; i < q; ++i){
            int q1, q2;
            scanf("%d%d", &q1, &q2);
            --q1; --q2;
            if(from[q2] >= q1){
                printf("%d\n", types[q2]);
            } else {
                printf("OK\n");
            }
        }
        scanf("%d%d", &m, &q);
        printf("\n");
    }
    return (0);
}