package main

import . "fmt"

func main() {
	var s string
	Scan(&s)
	var ans, x int
	b := []byte(s)
	for i := range b {
		for j := range b {
			b[i],b[j]=b[j],b[i]
			Sscan(string(b), &x)
			if x > ans {
				ans = x
			}
			b[i],b[j]=b[j],b[i]
		}
	}
	Println(ans)
}