#include <bits/stdc++.h>
using namespace std;
void RI() {}
template <typename... T>
void RI(int& head, T&... tail) {
  scanf("%d", &head);
  RI(tail...);
}
void RLL() {}
template <typename... T>
void RLL(long long& head, T&... tail) {
  scanf("%lld", &head);
  RLL(tail...);
}
void print() { putchar('\n'); }
template <typename T, typename... U>
void print(T head, U... tail) {
  cout << head << " ";
  print(tail...);
}
const int MOD = 1000000007;
int main() {
  int k, ans = 0;
  RI(k);
  for (int i = 0; i < (int)(k); i++) {
    int r;
    RI(r);
    ans = max(ans, r - 25);
  }
  printf("%d\n", ans);
  return 0;
}
