#include <iostream>

using namespace std;

int n, k;

int a[1001];

int main()

{

   cin >> n >> k;

   for (int i = 1; i <= n; ++i)

       cin >> a[i];

   int start1, start2;

   bool eBun;

   for (int i = 1; i < k; ++i) {

       start1 = (i - 1) * (n / k) + 1;

       for (int j = i + 1; j <= k; ++j) {

           start2 = (j - 1) * (n / k) + 1;

           eBun = 1;

           for (int p = 0; p < n / k; ++p) {

               if (a[start1 + p] != a[start2 + p]) {

                   eBun = 0;

                   break;

               }

           }

           if (eBun == 1) {

               cout << i << ' ' << j;

               return 0;

           }

       }

   }

   cout << "NU";

   return 0;
}