[Codeforces 115B] Lawnmower

题目传送门：点击传送

Time limit per test：2 seconds

Memory limit per test：256 megabytes

Description

You have a garden consisting entirely of grass and weeds. Your garden is described by an n × m grid, with rows numbered 1 to n from top to bottom, and columns 1 to m from left to right. Each cell is identified by a pair (r, c) which means that the cell is located at row r and column c. Each cell may contain either grass or weeds. For example, a 4 × 5 garden may look as follows (empty cells denote grass):

You have a land-mower with you to mow all the weeds. Initially, you are standing with your lawnmower at the top-left corner of the garden. That is, at cell (1, 1). At any moment of time you are facing a certain direction — either left or right. And initially, you face right.

In one move you can do either one of these:

1) Move one cell in the direction that you are facing.

if you are facing right: move from cell (r, c) to cell (r, c + 1)
if you are facing left: move from cell (r, c) to cell (r, c - 1)

2) Move one cell down (that is, from cell (r, c) to cell (r + 1, c)), and change your direction to the opposite one.

if you were facing right previously, you will face left
if you were facing left previously, you will face right

You are not allowed to leave the garden. Weeds will be mowed if you and your lawnmower are standing at the cell containing the weeds (your direction doesn't matter). This action isn't counted as a move.

What is the minimum number of moves required to mow all the weeds?

Input

The first line contains two integers n and m (1 ≤ n, m ≤ 150) — the number of rows and columns respectively. Then follow n lines containing m characters each — the content of the grid. "G" means that this cell contains grass. "W" means that this cell contains weeds.

It is guaranteed that the top-left corner of the grid will contain grass.

Output

Print a single number — the minimum number of moves required to mow all the weeds.

Examples

input

4 5
GWGGW
GGWGG
GWGGG
WGGGG

output

input

3 3
GWW
WWW
WWG

output

input

1 1
G

output

Note

For the first example, this is the picture of the initial state of the grid:

A possible solution is by mowing the weeds as illustrated below:

解析：

要你除草：W是杂草。开始在左上角向右，每次移动只能朝一个方向（左或者右），换行的时候会转方向。最后要求最小移动步数

如图，因为要找最小路径，可能会想到除完某一行的草(i1,j1)就直接下走，这样下一行在j1的某一边杂草是除不了的

所以不能单看一行来判断下走

解决办法是：把所有格子都走一遍，把两个杂草之间的距离相加即为答案（坐标差的绝对值之和）

（补充：有人跟我说这是叫曼哈顿距离，不懂不懂...）

代码

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <queue>
using namespace std;
char a[155][155];
int main()
{int n,m,ans=0;scanf("%d%d",&n,&m);getchar();int i,j;for(i=1;i<=n;i++)   //读图{for(j=1;j<=m;j++)a[i][j]=getchar();getchar();}int lasti=1,lastj=1;for(i=1;i<=n;i++){if(i%2==1)      //奇数行向右走   偶数行向左走{for(j=1;j<=m;j++)if(a[i][j]=='W'){ans+=abs(i-lasti)+abs(j-lastj);lasti=i;lastj=j;}}else{for(j=m;j>0;j--)if(a[i][j]=='W'){ans+=abs(i-lasti)+abs(j-lastj);lasti=i;lastj=j;}}}printf("%d\n",ans);return 0;
}

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