#include <bits/stdc++.h>
int main() {
  int N, M = 0;
  int may = 0;
  scanf("%d", &N);
  int aux;
  for (int i = 0; i < N; i++) {
    scanf("%d", &aux);
    if (aux > 25) {
      may++;
      if (aux > M) M = aux;
    }
  }
  int r = 0;
  if (may > 0) {
    r = M - 25;
  }
  printf("%d", r);
}
