#include <bits/stdc++.h>
const double eps = 1e-10;
using namespace std;
int n, m, k, b;
int in[100];
int answ = INT32_MAX;
int main() {
  scanf("%d", &k);
  for (int i = 0; i < k; i++) {
    scanf("%d", &in[i]);
  }
  sort(in, in + k);
  if (in[k - 1] - 25 <= 0) {
    printf("%d\n", 0);
    return 0;
  }
  printf("%d\n", in[k - 1] - 25);
}
