Problem:
Score: 200 points

Problem Statement

Takahashi will do a tap dance. The dance is described by a string S where each character is L, R, U, or D. These characters indicate the positions on which Takahashi should step. He will follow these instructions one by one in order, starting with the first character.

S is said to be easily playable if and only if it satisfies both of the following conditions:

Every character in an odd position (1-st, 3-rd, 5-th, \ldots) is R, U, or D.

Every character in an even position (2-nd, 4-th, 6-th, \ldots) is L, U, or D.

Your task is to print Yes if S is easily playable, and No otherwise.

Constraints

S is a string of length between 1 and 100 (inclusive).

Each character of S is L, R, U, or D.

Input

Input is given from Standard Input in the following format:

S

Output

Print Yes if S is easily playable, and No otherwise.

Sample Input 1

RUDLUDR

Sample Output 1

Yes

Every character in an odd position (1-st, 3-rd, 5-th, 7-th) is R, U, or D.

Every character in an even position (2-nd, 4-th, 6-th) is L, U, or D.

Thus, S is easily playable.

Sample Input 2

DULL

Sample Output 2

No

The 3-rd character is not R, U, nor D, so S is not easily playable.

Sample Input 3

UUUUUUUUUUUUUUU

Sample Output 3

Yes

Sample Input 4

ULURU

Sample Output 4

No

Sample Input 5

RDULULDURURLRDULRLR

Sample Output 5

Yes

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;
import java.io.*;
import java.math.*;
public class Main{
	static int mod = (int)1e9+7;
	public static PrintWriter out = new PrintWriter (new BufferedOutputStream(System.out));
	public static void main(String sp[])throws IOException{
		FastReader sc = new FastReader();
		String st = sc.next();
		int v=0;
		boolean b=true;
		for(int i=0;i<st.length();i+=2){
			if(st.charAt(i)=='R' || st.charAt(i)=='U' || st.charAt(i)=='D')
				v=0;
			else b=false;
		}
		for(int i=1;i<st.length();i+=2){
			if(st.charAt(i)=='L' || st.charAt(i)=='U' || st.charAt(i)=='D')
				v=0;
			else b=false;
		}
		if(b==true)
			System.out.println("Yes");
		else System.out.println("No");

	}
	
	public static class pair{
		int pos;
		int bomb;
	}
	
	
	public static int partition(int [] arr, int s, int e){
		
		int index=s;
		int pivot = arr[e];
		for(int i=s;i<=e-1;i++){
			if(arr[i]<=pivot){
				arr = swap(arr, index, i);
				index++;
			}
		}
		swap(arr,index,e);
		print(arr);
		return index;
	}
	
	public static int[] swap(int[] arr, int low, int high){
		int temp = arr[low];
		arr[low]=arr[high];
		arr[high]=temp;
		return arr;
	}
	
	
	public static long gcd(long a, long b){
		if(a==0)
			return b;
		
		return gcd(b%a,a);
	}
	
	public static void print(int[] arr){
		for(int i=0;i<arr.length;i++)
			System.out.print(arr[i]+" ");
		System.out.println();
	}
	

	public static class comp implements Comparator<pair>{
		public int compare(pair o1, pair o2){
			return o1.bomb-o2.bomb;
		}
	}
	public static class FastReader {
		BufferedReader br;
		StringTokenizer st;
	
 
		public FastReader() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}
 
		String next() {
			while (st == null || !st.hasMoreTokens()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (Exception r) {
					r.printStackTrace();
				}
			}
			return st.nextToken();
		}
 
		int nextInt() {
			return Integer.parseInt(next());//converts string to integer
		}
 
		double nextDouble() {
			return Double.parseDouble(next());
		}
 
		long nextLong() {
			return Long.parseLong(next());
		}
 
		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (Exception r) {
				r.printStackTrace();
			}
			return str;
		}
	}
	
}