#include <bits/stdc++.h>
using namespace std;
int n;
int a[10000000];
int ans;
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  int lol = *max_element(a + 1, a + 1 + n) - 25;
  if (lol < 0)
    cout << 0;
  else
    cout << lol;
}
