#include <bits/stdc++.h>
int main() {
  int a, b, c, n, max = 0, i, j, s[50];
  scanf("%d", &n);
  for (i = 0; i < n; i++) scanf("%d", &s[i]);
  for (i = 0; i < n; i++) {
    if (s[i] > max) max = s[i];
  }
  a = max - 25;
  if (a < 0)
    printf("0");
  else
    printf("%d", a);
  return 0;
}
