#include <bits/stdc++.h>
using namespace std;
#pragma GCC diagnostic ignored "-Wunused-result"
long long dp[100000];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long i, j, n, t;
  cin >> n;
  vector<long long> a;
  for ((i) = (0); (i) < (n); ++(i)) {
    cin >> t;
    a.push_back(t);
  }
  sort(a.begin(), a.end());
  if (a[n - 1] <= 25)
    cout << "0";
  else
    cout << a[n - 1] - 25;
  return 0;
}
