#include <iostream>
#include <algorithm>
#include <stdlib.h>
#include <string>
using namespace std;


int za(int ta, int yo,int i, int j){
if(-1<i && -1<j && ta>i && yo>j) return (i*yo)+j;
else return -1;
}
pair<int,int> mo(int ta,int yo,int m){
return make_pair(m/yo,m%yo);
}




int main() {
int ta,yo;
string s;
int ma[52][52]={0};
int re[2704]={0};
int minz=10000;
cin>>ta>>yo;
for(int i=0;i<ta;i++){

cin>>s;
for(int j=0;j<yo;j++){
if(s[j]=='.'){
ma[i][j]=0;
re[za(ta,yo,i,j)]=0;
}
else if(s[j]=='#'){
ma[i][j]=1;
re[za(ta,yo,i,j)]=1;
if(za(ta,yo,i,j)<minz) minz=za(ta,yo,i,j);

}

}
}
int ans=0,l;
//cout<<minz<<endl;
if(minz==10000) ans=0;
else{
	for(int k=1;k<ta*yo-minz;k++){
		//if(k>=ta*yo-minz) break;
		if(ans==0&&re[minz+k]==1){
		int co[2704]={0};
		for(int i=0;i<2704;i++) co[i]=re[i];
		co[minz+k]=2;
		l=minz+1;
		int dx=mo(ta,yo,minz+k).first-mo(ta,yo,minz).first;
		int dy=mo(ta,yo,minz+k).second-mo(ta,yo,minz).second;
		while(l<ta*yo){
			if(co[l]==1)	{
				if(za(ta,yo,dx+mo(ta,yo,l).first,dy+mo(ta,yo,l).second)<0) l=ta*yo+1;
				else if(co[za(ta,yo,dx+mo(ta,yo,l).first,dy+mo(ta,yo,l).second)]!=1) l=ta*yo+1;
				else co[za(ta,yo,dx+mo(ta,yo,l).first,dy+mo(ta,yo,l).second)]=2;
			}
			l=l+1;
		}
		if(l==ta*yo) ans=1;
	//	cout<<k<<"  ";
	//	for(int i=0;i<9;i++) cout<<co[i];
	//	cout<<endl;
		}
		
	}
}
if(ans==0) cout<<"NO"<<endl;
else cout<<"YES"<<endl;


return 0;
}