题目描述
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.
Input
Input is given from Standard Input in the following format:
S
Output
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.
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
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分