#include <bits/stdc++.h>
using namespace std;
const int max_n = 30;
long long a[max_n], sum;
int n, indx;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  for (int i = 1; i < a[n - 1]; i++) {
    if (i != a[indx])
      sum++;
    else
      indx++;
  }
  sum = sum - (25 - n);
  if (sum < 0) sum = 0;
  cout << sum;
  return 0;
}
