#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n, m, a, i = 0, cnt = 0, mh, res, ans = 0, b, c, sum = 0, in,
                         array[30];
  long long int lfirst, sec, third, mfirst, p, p2;
  set<pair<long long int, long long int>> vec;
  cin >> n;
  for (i = 0; i < n; i++) cin >> array[i];
  sort(array, array + n);
  p = array[n - 1];
  if (p <= 25)
    cout << 0 << endl;
  else
    cout << p - 25 << endl;
}
