题解 | #合法IP#

import java.util.Scanner;

//这题有点脑残，调节也不写清楚，纯纯的浪费时间
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNext()) { // 注意 while 处理多个 case
            String val = in.nextLine();
            String[] str = val.split("\\.");
            if(val.contains("+")||val.contains("-")){
                System.out.println("NO");
                return;
            }
            if (str.length != 4) {
                System.out.println("NO");
                return;
            }
            int count = 0;
            for (int i = 0; i < str.length; i++) {
                if (str[i].equals("") || (str[i].charAt(0) == '0' && str[i].length() > 1) || Integer.parseInt(str[i]) > 255 || Integer.parseInt(str[i]) < 0) {
                    System.out.println("NO");
                    return;
                }
            }
            System.out.println("YES");


        }
    }
}