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