#include <bits/stdc++.h>
using namespace std;
int main() {
  cin.sync_with_stdio(false);
  cin.tie(NULL);
  int n, x, mx = 0;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> x;
    mx = max(mx, x);
  }
  if (mx - 25 < 0) {
    cout << "0\n";
  } else {
    cout << mx - 25 << "\n";
  }
  return 0;
}
