package main

import (
	"fmt"
	"sort"
)

func main() {
	var x string
	fmt.Scan(&x)
	m := make(map[int]int, 0)
	for i := 0; i < len(x); i++ {
		m[int(x[i]-'0')]++
	}
	if (len(m)) == 1 {
		fmt.Println(-1)
		return
	}

	ks := make([]int, 0)
	for k := range m {
		ks = append(ks, k)
	}
	sort.Sort(sort.Reverse(sort.IntSlice(ks)))
	maxs := ""
	for i := range ks {
		for j := 0; j < m[ks[i]]; j++ {
			maxs += string('0' + byte(ks[i]))
		}
	}
	// fmt.Println("x", x, "maxs", maxs)
	var s string
	for i := len(maxs) - 1; i-1 >= 0; i-- {
		// fmt.Println("found diff on i", i)
		if maxs[i-1] != maxs[i] {
			s = maxs[0:i-1] + string(maxs[i]) + string(maxs[i-1])
			if i+1 < len(maxs) {
				s += string(maxs[i+1:])
			}
			break
		}
	}
	if s[0] == '0' {
		fmt.Println(-1)
	} else {
		fmt.Println(s)
	}
}