text: #include<iostream>
  #include<cstdio>
  #include<cstdlib>
  #include<cstring>
  #include<algorithm>
  using namespace std;
  
  #define ll long long
  #define mem(Arr,x) memset(Arr,x,sizeof(Arr))
  
  const int maxN=60;
  const int inf=2147483647;
  
  int n,m;
  char Input[maxN];
  ll Arr[maxN];
  
  int main()
  {
  	ios::sync_with_stdio(false);
  	
  	cin>>n>>m;
  	for (int i=1;i<=n;i++)
  	{
  		cin>>(Input+1);
  		for (int j=1;j<=m;j++)
  			if (Input[j]=='.') Arr[i]=Arr[i]<<1ll;
  			else Arr[i]=(Arr[i]<<1ll)|1ll;
  	}
  	bool flag=1;
  	for (int i=1;i<=n;i++)
  		for (int j=i+1;j<=n;j++)
  			if (((Arr[i]&Arr[j])!=0)&&(Arr[i]!=Arr[j])){
  				flag=0;break;
  			}
  	if (flag) cout<<"Yes"<<endl;
  	else cout<<"No"<<endl;
  	return 0;
  }
  