#include <iostream>
#include<vector>
using namespace std;

bool vizsgal( vector<unsigned int> &k,  unsigned int &b, unsigned int &e)
{
 int elofordulas = 0;
 unsigned int i = b-1;

 //cout << b << " " << e << endl; 

 while (i < e && elofordulas == 0)
 
 {
  
   unsigned int j=i+1;	
   while (j < e && elofordulas < 1)
	{
	if (k[i] == k[j]) elofordulas++;
	if (elofordulas == 1) cout << k[i] << endl; 
	j++;
	}
 i++; 
 }
if (elofordulas == 1) return true;
 return false;
}

int app(istream &f)
{
 unsigned int M;
 unsigned int Q;

 unsigned int b, e;

 vector<unsigned int> k;
 vector<unsigned int> u;
 
 string temp;

 for (;;)
 {
   f >> M >> Q;
   if (M == 0 && Q == 0) return 0;
   for (unsigned int i=0;i<M;i++)
   {
     f >> e; 
     k.push_back(e);
   }
   for (unsigned int i=0;i<Q;i++)
   {
     f >> b >> e; 
     if (vizsgal(k,b,e) == false) { cout << "OK" << endl; }
     
   }
   cout << endl;
  getline(f,temp);
  k = u;	
 }
 return 0;

}


int main()
{
  app(cin);

  return 0;
}