#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:64000000")
using namespace std;
const long long K = 1;
set<int> S;
int main() {
  int n, i, x;
  cin >> n;
  for (i = 0; i < n; ++i) {
    cin >> x;
    S.insert(x);
  }
  i = 0;
  while (S.size() < 25) {
    i++;
    S.insert(i);
  }
  cout << *S.rbegin() - 25;
  return 0;
}
