#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  long x;
  vector<long> v;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> x;
    v.push_back(x);
  }
  sort(v.begin(), v.end(), greater<int>());
  x = v[0];
  if (x > 25) {
    cout << x - 25;
  } else {
    cout << 0;
  }
  return 0;
}
