#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  vector<int> a(100, 0);
  int b;
  for (int i = 0; i < n; i++) {
    cin >> b;
    b--;
    a[b]++;
  }
  sort(a.begin(), a.end());
  int s = 0;
  s = a[99] / k;
  if (a[99] % k > 0) {
    s++;
  }
  int l = 0;
  for (int i = 99; i >= 0; i--) {
    if (a[i] > 0) {
      l++;
    }
  }
  cout << s * k * l - n;
  return 0;
}
