Codeforces Round 125 (Div. 1)
B
Jumping on Walls
Codeforces
1400
原题
← AC →
翻译中…

Vasya plays a computer game with ninjas. At this stage Vasya's ninja should get out of a deep canyon.

翻译中…

The canyon consists of two vertical parallel walls, their height is $*n*$ meters. Let's imagine that we split these walls into $1$ meter-long areas and number them with positive integers from $1$ to $*n*$ from bottom to top. Some areas are safe and the ninja can climb them. Others are spiky and ninja can't be there. Let's call such areas dangerous.

翻译中…

Initially the ninja is on the lower area of the left wall. He can use each second to perform one of the following actions:

翻译中…
  • climb one area up;
  • climb one area down;
  • jump to the opposite wall. That gets the ninja to the area that is exactly $*k*$ meters higher than the area he jumped from. More formally, if before the jump the ninja is located at area $*x*$ of one wall, then after the jump he is located at area $*x* + *k*$ of the other wall.
翻译中…

If at some point of time the ninja tries to get to an area with a number larger than $*n*$, then we can assume that the ninja got out of the canyon.

翻译中…

The canyon gets flooded and each second the water level raises one meter. Initially the water level is at the lower border of the first area. Ninja cannot be on the area covered by water. We can assume that the ninja and the water "move in turns" — first the ninja performs some action, then the water raises for one meter, then the ninja performs one more action and so on.

翻译中…

The level is considered completed if the ninja manages to get out of the canyon.

翻译中…

After several failed attempts Vasya started to doubt whether it is possible to complete the level at all. Help him answer the question.

翻译中…

Input

翻译中…

The first line contains two integers $*n*$ and $*k*$ ($1 ≤ *n*, *k* ≤ 10^{5}$) — the height of the canyon and the height of ninja's jump, correspondingly.

翻译中…

The second line contains the description of the left wall — a string with the length of $*n*$ characters. The $*i*$-th character represents the state of the $*i*$-th wall area: character "X" represents a dangerous area and character "-" represents a safe area.

翻译中…

The third line describes the right wall in the same format.

翻译中…

It is guaranteed that the first area of the left wall is not dangerous.

翻译中…

Output

翻译中…

Print "YES" (without the quotes) if the ninja can get out from the canyon, otherwise, print "NO" (without the quotes).

翻译中…

Note

翻译中…

In the first sample the ninja should first jump to the right wall, then go one meter down along the right wall, then jump to the left wall. The next jump can get the ninja from the canyon.

翻译中…

In the second sample there's no way the ninja can get out of the canyon.

翻译中…

样例

Input #1
7 3
---X--X
-X--XX-
Output #1
YES
InputCopy OutputCopy
Input #2
6 2
--X-X-
X--XX-
Output #2
NO
InputCopy OutputCopy
题目信息
题号
198B
时间限制
2 s
内存限制
256 MB
标签
最短路

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。