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 Python (3.4.3) (judge verdict: Accepted)

def examA():
    W = {'Sunny':'Cloudy','Cloudy':'Rainy','Rainy':'Sunny'}
    S = SI()
    ans = W[S]
    print(ans)
    return

def examB():
    R = {"R","U","D"}
    L = {"L","U","D"}
    S = SI()
    ans = "Yes"
    for i,s in enumerate(S):
        if i%2==0 and s in R:
            continue
        if i%2==1 and s in L:
            continue
        ans = "No"
        break
    print(ans)
    return

def examC():
    ans = 0
    print(ans)
    return

def examD():
    ans = 0
    print(ans)
    return

def examE():
    # https://tjkendev.github.io/procon-library/python/string/z-algorithm.html
    def z_algo(S):
        N = len(S)
        A = [0] * N
        i = 1; j = 0
        A[0] = l = len(S)
        while i < l:
            while i + j < l and S[j] == S[i + j]:
                j += 1
            if not j:
                i += 1
                continue
            A[i] = j
            k = 1
            while l - i > k < j - A[k]:
                A[i + k] = A[k]
                k += 1
            i += k; j -= k
        return A
    N = I()
    S = SI()
    ans = 0
    for i in range(N):
        Z = z_algo(S[i:])
        for k,n in enumerate(Z[1:]):
            cur = min(k+1,n)
            ans = max(ans,cur)
    print(ans)
    return

def examF():
    ans = 0
    print(ans)
    return

import sys,copy,bisect,itertools,heapq,math,random
from heapq import heappop,heappush,heapify
from collections import Counter,defaultdict,deque
def I(): return int(sys.stdin.readline())
def LI(): return list(map(int,sys.stdin.readline().split()))
def LSI(): return list(map(str,sys.stdin.readline().split()))
def LS(): return sys.stdin.readline().split()
def SI(): return sys.stdin.readline().strip()
global mod,mod2,inf,alphabet,_ep
mod = 10**9 + 7
mod2 = 998244353
inf = 10**18
_ep = 10**(-12)
alphabet = [chr(ord('a') + i) for i in range(26)]

if __name__ == '__main__':
    examB()

"""

"""