#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  int mx = 0, res = 0;
  for (int i = 1; i <= n; i++) {
    int j;
    cin >> j;
    mx = max(j, mx);
  }
  if (mx > 25) {
    res = mx - 25;
  }
  cout << res << endl;
}
