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#pragma GCC optimize "-O3"
#include <bits/stdc++.h>
#include <tr1/unordered_map>
using namespace std;
#define fast ios_base::sync_with_stdio(0)
// #define ll long long int
#define llu unsigned long long int
#define I int
#define S string
#define D double
#define rep(i,a,b) for(int i=a;i<b;i++)
#define repr(i,a,b) for(int i=a;i>b;i--)
#define in(n) scanf("%lld",&n)
#define in2(a,b) scanf("%lld %lld",&a,&b)
#define in3(a,b,c) scanf("%lld %lld %lld",&a,&b,&c)
#define out(a) printf("%lld\n",a)
#define inu(a) scanf("%lld",&a)
#define outu(a) printf("%llu",a)
#define outf(a) printf("%.9f\n", a);
#define mod 1000000007
#define inf 100000000000000
#define MM(a,x)  memset(a,x,sizeof(a));
#define ALL(x)   (x).begin(), (x).end()
#define UN(v)    sort(ALL(v)), v.resize(unique(ALL(v))-v.begin())
#define MP make_pair
#define PB push_back
#define f first
#define s second
#define sz(v) v.size()
#define yes cout<<"Yes"<<endl
#define no cout<<"No"<<endl
#define nl cout<<"\n"
#define MX1 100005
#define MX2 1000005
#define bs binary_search
#define lb lower_bound
#define ub upper_bound
// typedef pair<ll,ll>  pll;
// typedef vector<ll>     vll;
// typedef vector<llu>    vllu;
typedef vector<string>  vs;
// typedef vector<pll>     vpll;
int main(){
	fast;
	// freopen("A-large-practice.in","r",stdin);
	// freopen("output_file_name.out","w",stdout);
	long long n , m ;
	in2(n,m);
	vs vs;
	rep(i,0,n){
		S s;
		cin >> s;
		vs.PB(s);
	}
	int rowfinished[100];
	rep(i,0,100)
		rowfinished[i] = 0;
	rep(i,0,n){
		rep(j,i+1,n){
			if(vs[i] == vs[j]){
				rowfinished[j] = 1;
				continue;
			}
			rep(k,0,m){
				if(vs[i][k]== vs[j][k] && vs[i][k] == '#'){
					no;
					return(0);
				}
			}
		}
		rowfinished[i] = 1;
	}
	yes;
}