#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
const long long inf = 1e18;
bool sortbysec(const pair<long long, long long> &a,
               const pair<long long, long long> &b) {
  if (a.first == b.first) return (a.second > b.second);
}
signed main() {
  long long t = 1;
  while (t--) {
    long long k;
    cin >> k;
    long long r[k];
    for (long long i = 0; i <= k - 1; i++) cin >> r[i];
    long long m = *max_element(r, r + k);
    if (m <= 25)
      cout << 0 << endl;
    else
      cout << m - 25 << endl;
  }
}
