#include <bits/stdc++.h>
using namespace std;
inline int nxt() {
  int first;
  scanf("%d", &first);
  return first;
}
inline void out(int a) { printf("%d ", a); }
int main() {
  int n = nxt(), mx = 0, md = 0;
  for (int i = 0; i < n; i++) {
    int tmp = nxt();
    mx = max(mx, tmp);
  }
  if (mx > 25)
    out(mx - 25);
  else
    cout << 0;
  return 0;
}
