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