macro_rules! read {
  ($x:ident, $v:expr, $idx:expr, $type:ty) => {
    let $x:$type = $v[$idx].clone().parse().unwrap();
  };

  ( $($x:ident:$t:ty),* ) => {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    let input:Vec<String> = s.trim()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect();
    let mut idx:i64 = -1;
    $(
      idx += 1;
      read!($x, input, idx as usize, $t);
    )*
  };
}

fn main() {
  read!(sa:String, pa:String, _xa:String);
  read!(sb:String, pb:String, _xb:String);

  let pa:Vec<i32> = pa.chars().map(|x| x.to_string().parse().unwrap()).collect();
  let pb:Vec<i32> = pb.chars().map(|x| x.to_string().parse().unwrap()).collect();
  let ans = if pa.len() > pb.len() {
    sa
  } else if pa.len() < pb.len() {
    sb
  } else if pa > pb {
    sa
  } else if pa < pb {
    sb
  } else {
    "-1".to_string()
  };
  println!("{}", ans);
}