#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, a, tmp;
  while (a = 0, ~scanf("%d", &n)) {
    while (n--) scanf("%d", &tmp), a = max(a, tmp);
    printf("%d\n", max(a - 25, 0));
  }
  return 0;
}
