#include <bits/stdc++.h>
using namespace std;
int a, b, n;
void setup() {}
void solve() {
  cin >> n;
  for (int i = 1; i <= n; ++i) {
    cin >> a;
    b = max(b, a);
  }
  cout << max(0, b - 25);
}
int main() {
  setup();
  solve();
  return 0;
}
