#include <bits/stdc++.h>
using namespace std;
void Arr2DInit(vector<vector<int> > &a, int n, int m) {
  a.resize(n);
  for (int i = 0; i < n; i++) a[i].resize(m);
}
template <class T>
T minn(T a, T b) {
  return a < b ? a : b;
}
template <class T>
T maxx(T a, T b) {
  return a > b ? a : b;
}
long long Pow(long long a, long long n) {
  if (n == 0) return 1;
  if (n == 1) return a;
  if (n % 2 == 0)
    return Pow(a, n / 2) * Pow(a, n / 2);
  else
    return Pow(a, n / 2) * Pow(a, n / 2) * a;
}
const int dx[] = {0, 0, 1, -1};
const int dy[] = {1, -1, 0, 0};
string direct = "UDRL";
struct SAVE {
  int a, b, i;
};
bool Cmp(SAVE a, SAVE b) { return abs(a.a - a.b) > abs(b.a - b.b); }
int main() {
  int n, x, maxrank = 0;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> x;
    maxrank = maxx(maxrank, x);
  }
  cout << maxx(0, maxrank - 25);
}
