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 C (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <float.h>
 
#pragma region 定義
#define i_cin(X) scanf("%d", &X)
#define i_cin2(X,Y) scanf("%d %d",&X,&Y)
#define i_cin4(X,Y,Z,W) scanf("%d %d %d %d",&X,&Y,&Z,&W)
#define i_cin3(X,Y,Z) scanf("%d %d %d",&X,&Y,&Z)
#define l_cin(X) scanf("%ld",&X)
#define f_cin(X) scanf("%f",&X)
#define l_cin2(X,Y) scanf("%ld %ld",&X,&Y)
#define s_cin(X) scanf("%s",&X)
#define ll_cin(X) scanf("%lld", &X)
 
#define  i_cout(X) printf("%d\n",X)
#define  f_cout(X) printf("%g\n",X)
#define  i_cout2(X,Y) printf("%d %d\n",X,Y)
#define  l_cout(X) printf("%ld\n",X)
#define  s_cout(X) printf("%s\n",X)
#define  ll_cout(X) printf("%lld\n",X)
 
typedef long long  ll;
#define rept(x, s, n) for (int x = s; x < n; x++)
 
#define S_RTN(S)  s_cout(S);return 0
 
 
#define _itoa(A,N) sprintf(A, "%d", N);
 
int i_cins(int n, int* A);
int l_cins2(int n, long* A, long* B);
int s_dsort(const void* a, const void* b);
int s_asort(const void* a, const void* b);
 
int  _gcd(int a, int b);
int  _swp(int* a, int* b);
int _cknum(char* a, int n);
int _atoi(char* s, int len);
 
int _gcd(int a, int b) {
    int r, tmp;
    if (a < b) { tmp = a; a = b; b = tmp; }
    r = a % b;
    while (r) {
        if (!r) break;
        a = b; b = r;
        r = a % b;
    }
    return(b);
}


//小さい順
int compare_int(const void *a, const void *b)
{
    return *(int*)a - *(int*)b;
}

//変換(文字から整数)
int ctoi(char c) {
    if (c >= '0' && c <= '9') {
        return c - '0';
    }
    return 0;
}

//要素数
int HM(char a[]){
    int cnt=0;
    while(a[cnt]!=0){
        cnt++;
    }
    return cnt;
}

int main(void){
    char stp[100];
    scanf("%s",stp);
    int size=0;
    size=HM(stp);
    for(int i=0;i<size;i+=2){
        if(stp[i]!='R'&&stp[i]!='U'&&stp[i]!='D'){
            printf("No");
            return 0;
        }
    }
    for(int i=1;i<size;i+=2){
        if(stp[i]!='L'&&stp[i]!='U'&&stp[i]!='D'){
            printf("No");
            return 0;
        }
    }
    printf("Yes");
    
    
}