#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  vector<int> a(n);
  for (int i = 0; i < n; i++) {
    scanf("%d", &a[i]);
  }
  int m = *max_element(a.begin(), a.end());
  printf("%d", max(0, m - 25));
}
