A labyrinth is the rectangular grid, each of the cells of which is either free or wall, and it's possible to move only between free cells sharing a side.

Constantine and Mike are the world leaders of composing the labyrinths. Each of them has just composed one labyrinth of size n × m, and now they are blaming each other for the plagiarism. They consider that the plagiarism takes place if there exists such a path from the upper-left cell to the lower-right cell that is the shortest for both labyrinths. Resolve their conflict and say if the plagiarism took place.

#include <cstdio>
#include <cmath>
#include <cstring>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <set>
#include <vector>
#include <sstream>
#include <queue>
#include <typeinfo>
#include <fstream>
#include <map>
#include <stack>
typedef long long ll;
using namespace std;
//freopen("D.in","r",stdin);
//freopen("D.out","w",stdout);
#define sspeed ios_base::sync_with_stdio(0);cin.tie(0)
#define test freopen("test.txt","r",stdin)
#define maxn 2000001
#define mod 10007
#define eps 1e-9
const int inf=0x3f3f3f3f;
const ll infll = 0x3f3f3f3f3f3f3f3fLL;
inline ll read()
{ll x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}return x*f;
}
//**************************************************************************************int a1[510][510];
int a2[510][510];
string s;
struct node
{int x,y,z;
};
int dx[4]={1,-1,0,0};
int dy[4]={0,0,1,-1};
int vis[510][510];
int main()
{int n=read(),m=read();for(int i=0;i<n;i++){cin>>s;for(int j=0;j<m;j++){if(s[j]=='.')a1[i][j]=1;elsea1[i][j]=0;}}for(int i=0;i<n;i++){cin>>s;for(int j=0;j<m;j++){if(s[j]=='.')a2[i][j]=1;elsea2[i][j]=0;}}queue<node> q;q.push((node){0,0,0});int flag=0;int ans1=inf;memset(vis,0,sizeof(vis));vis[0][0]=1;while(!q.empty()){node now=q.front();q.pop();if(now.x==n-1&&now.y==m-1&&ans1>now.z){ans1=now.z;continue;}for(int i=0;i<4;i++){node next;next.x=now.x+dx[i];next.y=now.y+dy[i];next.z=now.z;if(next.x<0||next.x>=n)continue;if(next.y<0||next.y>=m)continue;if(vis[next.x][next.y]||a1[next.x][next.y]==0)continue;vis[next.x][next.y]=1;q.push((node){next.x,next.y,next.z+1});}}while(!q.empty())q.pop();q.push((node){0,0,0});int ans2=inf;memset(vis,0,sizeof(vis));vis[0][0]=1;while(!q.empty()){node now=q.front();q.pop();if(now.x==n-1&&now.y==m-1&&ans2>now.z){ans2=now.z;continue;}for(int i=0;i<4;i++){node next;next.x=now.x+dx[i];next.y=now.y+dy[i];next.z=now.z;if(next.x<0||next.x>=n)continue;if(next.y<0||next.y>=m)continue;if(vis[next.x][next.y]||a2[next.x][next.y]==0)continue;vis[next.x][next.y]=1;q.push((node){next.x,next.y,next.z+1});}}if(ans1!=ans2){puts("NO");return 0;}while(!q.empty())q.pop();q.push((node){0,0,0});memset(vis,0,sizeof(vis));vis[0][0]=1;while(!q.empty()){if(flag)break;node now=q.front();q.pop();if(now.x==n-1&&now.y==m-1&&now.z==ans1)flag=1;if(flag)break;for(int i=0;i<4;i++){node next;next.x=now.x+dx[i];next.y=now.y+dy[i];next.z=now.z+1;if(next.x<0||next.x>=n)continue;if(next.y<0||next.y>=m)continue;if(vis[next.x][next.y]||a1[next.x][next.y]==0||a2[next.x][next.y]==0)continue;vis[next.x][next.y]=1;q.push((node){next.x,next.y,next.z});}}if(flag)puts("YES");elseputs("NO");}