#include <iostream>
#include<cstdio>
#include<vector>
#include <set>

using namespace std;

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

 for (;;)
 {
   f >> M >> Q;
   if (M == 0 && Q == 0) return 0;

   vector<unsigned int> be(M);
   vector<unsigned int> kezd(Q);
   vector<unsigned int> veg(Q);
   vector<int> ret(Q,-1);

   for (unsigned int i=0;i<M;i++)
   {
     f >> be[i]; 
   }
   for (unsigned int i=0;i<Q;i++)
   {
     f >> kezd[i] >> veg[i] ;
     kezd[i]--;
     veg[i]--;     
   }
   unsigned int l = 0;
   while(l<Q)
   { 
	for (unsigned int i=0;i<M;i++)
	   {
		vector<set<int> > h(10000);
	  	for (unsigned int j=l;j<Q && j<l+10000;j++)
	  	{
			if (ret[j] == -1)
			{
				if (kezd[j]<=i && i<=veg[j])
				{
					if (h[j-l].count(be[i]) > 0) ret[j] = be[i];
					else h[j-l].insert(be[i]);
				}
			}
		}
	   }
	l += 10000;
}

  for (unsigned int i=0;i<Q;i++)
   {
     if (ret[i] == -1) cout << "OK" << endl;
     else cout<< ret[i] << endl;
   }

   cout << endl;
   getline(f,temp);	
 }
 return 0;

}


int main()
{
  app(cin);

  
  return 0;
}