package main

import (
	"fmt"
	"strings"
)

func main() {
	var n int
	fmt.Scan(&n)
	var s string
	fmt.Scan(&s)

	if s == "0" {
		fmt.Println("0")
		return
	}

	zeros := strings.Count(s, "0")
	fmt.Print("1")
	fmt.Println(strings.Repeat("0", zeros))
}