#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1e9 + 7;
const long long MAXN = 100500 * 5;
const long long INF = 1e18;
int main() {
  long long n;
  cin >> n;
  long long mx = -1;
  for (int i = 1; i <= n; i++) {
    long long a;
    cin >> a;
    mx = max(a, mx);
  }
  if (mx <= 25) {
    cout << 0;
  } else {
    cout << mx - 25;
  }
}
