#include <bits/stdc++.h>
using namespace std;
int main(int argc, char* argv[]) {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int k;
  cin >> k;
  vector<int> v;
  for (int i = 0; i < k; ++i) {
    int t;
    cin >> t;
    v.push_back(t);
  }
  v.push_back(0);
  sort(v.begin(), v.end());
  if (v[v.size() - 1] < 25) v.push_back(25);
  int n = k - 25;
  int c = 0;
  for (int i = 1; i < v.size(); ++i) {
    c += v[i] - v[i - 1] - 1;
  }
  cout << max(c + n, 0) << endl;
  return 0;
}
