#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int a[n];
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  for (int i = 0; i < n - 1; i++) {
    int m = i;
    for (int j = i + 1; j < n; j++) {
      if (a[m] > a[j]) m = j;
    }
    int t = a[m];
    a[m] = a[i];
    a[i] = t;
  }
  int b = a[n - 1];
  int c = 0;
  if (b > 25) {
    cout << b - 25;
  } else
    cout << c;
}
