#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<long long, long long>;
using pcc = pair<char, char>;
using pdd = pair<double, double>;
using pci = pair<char, int>;
using si = set<int>;
using s = string;
using seti = set<int>;
using useti = unordered_set<int>;
using mseti = multiset<int>;
using umseti = unordered_multiset<int>;
using vi = vector<int>;
using vc = vector<char>;
using vs = vector<string>;
using vd = vector<double>;
using vll = vector<ll>;
using vpii = vector<pii>;
using msi = map<string, int>;
using umsi = unordered_map<string, int>;
void solve() {
  int n;
  cin >> n;
  vi v(n);
  for (auto &t : v) {
    cin >> t;
  }
  sort(v.rbegin(), v.rend());
  if (v[0] <= 25) {
    cout << 0 << "\n";
  } else {
    cout << v[0] - 25 << "\n";
  }
}
int main() {
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(nullptr);
  cout.tie(nullptr);
  solve();
  return 0;
}
