#include <bits/stdc++.h>
using namespace std;
int a[1000001], k, mx, t;
int main() {
  cin >> k;
  for (int i = 0; i < k; i++) cin >> a[i];
  mx = a[0];
  for (int i = 1; i < k; i++)
    if (a[i] > mx) mx = a[i];
  if (mx > 25)
    cout << mx - 25 << endl;
  else
    cout << '0';
}
