#include <bits/stdc++.h>
using namespace std;
int main() {
  int K;
  while (cin >> K) {
    int arr[K], cou = 0;
    for (int i = 0; i < K; i++) {
      cin >> arr[i];
    }
    sort(arr, arr + K);
    if (arr[K - 1] <= 25) {
      cout << 0 << endl;
      return 0;
    } else {
      cout << arr[K - 1] - 25 << endl;
    }
  }
  return 0;
}
