package main

import (
	"fmt"
)

func main() {
	var N int
	var S string
	fmt.Scanln(&N)
	fmt.Scanln(&S)

	if N < 2 {
		fmt.Println("NO")
		return
	}
	if N == 2 {
		if S == "00" || S == "11" {
			fmt.Println("YES")
		} else {
			fmt.Println("NO")
		}
		return
	}
	if N == 3 {
		if S == "010" || S == "101" {
			fmt.Println("NO")
		} else {
			fmt.Println("YES")
		}
		return
	}
	fmt.Println("YES")
}