#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, a = -1;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    int A;
    scanf("%d", &A);
    a = max(a, A);
  }
  cout << max(0, a - 25) << endl;
  return 0;
}
