#include <bits/stdc++.h>
using namespace std;
const int maxn = 22;
const long long mod = 1e9 + 7;
const int inf = 0x3f3f3f3f;
int main() {
  if (fopen("/home/lianyi/123.txt", "r") != NULL) {
    freopen("/home/lianyi/123.txt", "r", stdin);
  } else {
    std::ios::sync_with_stdio(false);
    cin.tie(0);
  }
  int n;
  while (cin >> n) {
    int mx = 0;
    for (int i = 1; i <= n; i++) {
      int v;
      cin >> v;
      mx = max(v, mx);
    }
    if (mx <= 25) {
      cout << '0' << '\n';
    } else {
      cout << mx - 25 << '\n';
    }
  }
  return 0;
}
