void main() {
  int a1, b1, a2, b2, a3, b3;
  cin >> a1 >> b1 >> a2 >> b2;
  a3 = (a1>a2)?a1:a2;
  b3 = (b1<b2)?b1:b2;

  if (a3 <= b3) cout << "[" << a3 << "," << b3 << "]";
  else cout << "[]";
}