fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    
    let mut n: Vec<String> = n.trim().chars().map(|c| c.to_string()).collect();
    n.sort_by(|a, b| b.cmp(a));

    let mut border = 0;
    let tail = n.len() - 1;
    for i in 0..tail {
        if &n[tail-i-1] != &n[tail-i] {
            border = tail-i-1;
            break;
        }
    }

    if border == 0 {
        println!("-1");
    } else {
        n.swap(border, border+1);
        println!("{}", n.join(""));
    }
}