#include <bits/stdc++.h>
using namespace std;
int c[100];
int main() {
  int n, k;
  scanf("%d%d", &n, &k);
  for (int i = 0; i < n; i++) scanf("%d", &c[i]);
  int s = 0, mt = 1;
  for (int i = 0; i < k; i++) mt *= c[i];
  for (int i = k; i < n; i++) {
    int temp = mt;
    temp *= c[i];
    temp /= c[s++];
    mt = max(mt, temp);
  }
  sort(c, c + n);
  int res = 1;
  for (int i = n - 1; i >= n - k; i--) {
    res *= c[i];
  }
  if (res == mt && n == 3)
    puts("NO GAME");
  else
    printf("%d\n", res - mt);
}
