题解 | #合法IP#

import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            String[] str = sc.nextLine().split("\\.");
            boolean flag = true;
            if(str.length == 4){
                for(int i = 0; i < 4; i++){
                    if(str[i].equals("")){
                        flag = false;
                        break;
                    }else if(str[i].length()>1 && str[i].charAt(0)=='0'){
                        flag = false;
                        break;
                    }else if(str[i].replaceAll("[0-9]","").length() != 0){
                        flag = false;
                        break;
                    }else if(Integer.parseInt(str[i])<0 || Integer.parseInt(str[i])>255){
                        flag = false;
                        break;
                    }else{
                        flag = true;
                    }
                }
            }else{
                flag = false;
            }
            
            if(flag == true){
                System.out.println("YES");
            }else{
                System.out.println("NO");
            }
        }
    }
}