#include <bits/stdc++.h>
using namespace std;
inline int read() {
  char ch = getchar();
  if (!(~ch)) return 0;
  int f = 1;
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  int x = 0;
  while (ch >= '0' && ch <= '9') {
    x = (x << 3) + (x << 1) + (ch ^ 48);
    ch = getchar();
  }
  return x * f;
}
int main() {
  int n = read(), maxn = 0;
  while (n--) maxn = max(maxn, read());
  if (maxn < 25)
    puts("0");
  else
    printf("%d\n", maxn - 25);
  return 0;
}
