#include <bits/stdc++.h>
using namespace std;
int a[1000010];
bool cmp(int x, int y) { return x > y; }
int main() {
  int k, maxn;
  while (~scanf("%d", &k)) {
    maxn = 0;
    for (int i = 0; i < k; i++) {
      scanf("%d", &a[i]);
      maxn = max(a[i], maxn);
    }
    int ans = maxn - 25;
    if (ans < 0) ans = 0;
    printf("%d\n", ans);
  }
  return 0;
}
