#include <bits/stdc++.h>
using namespace std;
using namespace std;
int main() {
  int n, a, b, c, x, y, z, mx = 0;
  long long s = 0;
  int ar[100] = {0};
  string st, ss;
  cin >> a;
  for (int i = 0; i < a; ++i) {
    cin >> b;
    mx = max(mx, b);
  }
  if (mx <= 25) {
    cout << "0";
  } else {
    cout << mx - 25;
  }
  return 0;
}
