#include <bits/stdc++.h>
using namespace std;
const int N = 1e6;
const int INF = 2e9;
int a[30];
int main() {
  int y, k;
  cin >> k;
  int MAX = -1;
  for (int i = 0; i < k; i++) {
    cin >> y;
    MAX = max(MAX, y);
  }
  cout << max(MAX - 25, 0) << endl;
}
