#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int K, r, ans = 0;
  scanf("%d", &K);
  for (int i = 0; i < K; ++i) {
    scanf("%d", &r);
    ans = max(ans, max(0, r - 25));
  }
  printf("%d\n", ans);
}
