#include <bits/stdc++.h>
using namespace std;
int main() {
  ofstream fout;
  ifstream fin;
  ios_base::sync_with_stdio(false);
  ios::sync_with_stdio(false);
  long long int n;
  cin >> n;
  vector<long long int> v;
  for (long long int i = 0; i < n; i++) {
    long long int temp;
    cin >> temp;
    v.push_back(temp);
  }
  long long int y = *max_element(v.begin(), v.end()) - 25;
  if (y < 0) y = 0;
  cout << y;
  return 0;
}
