#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, Max = INT_MIN;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int temp;
    cin >> temp;
    if (temp > Max) {
      Max = temp;
    }
  }
  if (Max < 25) {
    cout << 0;
  } else {
    cout << Max - 25;
  }
  return 0;
}
