#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, k, n, maxi = INT_MIN;
  cin >> n;
  for (i = 0; i < n; i++) {
    cin >> j;
    maxi = max(j, maxi);
  }
  if (maxi > 25)
    cout << maxi - 25;
  else
    cout << 0;
}
