#include <bits/stdc++.h>
using namespace std;
const long double PI = acos(-1.0);
template <typename T>
T abs(T x) {
  return x > 0 ? x : -x;
}
template <typename T>
T sqr(T x) {
  return x * x;
}
template <typename T>
bool chmin(T &x, T y) {
  if (x > y) {
    x = y;
    return true;
  }
  return false;
}
template <typename T>
bool chmax(T &x, T y) {
  if (x < y) {
    x = y;
    return true;
  }
  return false;
}
template <typename U, typename V>
ostream &operator<<(ostream &s, const pair<U, V> &x) {
  s << "(" << x.fst << ", " << x.snd << ")";
  return s;
}
template <typename U>
ostream &operator<<(ostream &s, const vector<U> &x) {
  s << "[";
  bool was = false;
  for (auto it : x) {
    if (was) {
      s << ", ";
    }
    was = true;
    s << it;
  }
  s << "]";
  return s;
}
template <typename U>
ostream &operator<<(ostream &s, const set<U> &x) {
  s << "{";
  bool was = false;
  for (auto it : x) {
    if (was) {
      s << ", ";
    }
    was = true;
    s << it;
  }
  s << "}";
  return s;
}
template <int sz>
ostream &operator<<(ostream &s, const bitset<sz> &x) {
  for (int i = 0; i < sz; i++) {
    s << x[i];
  }
  return s;
}
int main() {
  srand(time(0));
  int k;
  cin >> k;
  int maxi = 25;
  while (k--) {
    int p;
    cin >> p;
    chmax(maxi, p);
  }
  cout << maxi - 25 << endl;
  return 0;
}
