#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, rank, m;
  cin >> n;
  cin >> rank;
  for (int i = 1; i < n; i++) {
    cin >> m;
    if (rank < m) rank = m;
  }
  if (rank > 25)
    cout << rank - 25 << endl;
  else
    cout << 0 << endl;
  return 0;
}
