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import java.util.*;


import java.io.*;
import java.lang.*;
import java.lang.reflect.Array;
import java.math.*;

public class cf3 
{
	static class pair implements Comparable<pair>
	 {
		Integer x,y;
		pair(int x,int y)
		{
			this.x=x;
			this.y=y;
		}
		public int compareTo(pair o)
		{
			if(x<o.x)
				return -1;
			else
				return 1;
		}  
	}
	static int ans=0;
	static long mod=1000000007;
	static boolean prime[];
	
	public static void main(String args[])
	{
		InputReader in=new InputReader(System.in);
		PrintWriter pw=new PrintWriter(System.out);
		int n=in.nextInt();
		int m=in.nextInt();
		String[] str=new String[n];
		for(int i=0;i<n;i++)
			str[i]=in.nextLine();
		HashSet<String> set=new HashSet<>();
		boolean[] arr=new boolean[m];
		for(int i=0;i<n;i++)
			set.add(str[i]);
		for(int i=0;i<m;i++)
			arr[i]=false;
		boolean flag=false;
		for(String s:set)
		{
			for(int i=0;i<m;i++)
			{
				if(s.charAt(i)=='#')
				{
					if(!arr[i])
						arr[i]=true;
					else
					{
						flag=true;
						break;
					}
				}
			}
			if(flag)
				break;
		}
		if(flag)
			pw.println("No");
		else
			pw.println("Yes");
		pw.flush();
	}
	public static int distance(int x,int y,int p,int q)
	{
		int a=(x-p)*(x-p);
		int b=(y-q)*(y-q);
		int dis=a+b;
		return dis;
	}
	public static int bnum(int num)
	{
		int ans=0;
		for(int i=31;i>=0;i--)
		{
			if((num&(1<<i))!=0)
			{
				ans+=Math.pow(10,i);
			}
		}
		return ans;
	}
	public static int bsdown(int a[],int item)
	{
		int low=0,high=a.length-1,ans=-1;
		while(low<=high)
		{
			int mid=low+(high-low)/2;
			if(a[mid]<=item)
			{
				ans=mid;
				low=mid+1;
			}
			else
				high=mid-1;
				
		}
		return ans;
	}
	public static long inverse(long num)
	{
		return fastpow(num,mod-2,mod);
	}
	public static int bsupper(int a[],int item)
	{
		int low=0,high=a.length-1,ans=-1;
		while(low<=high)
		{
			int mid=low+(high-low)/2;
			if(a[mid]>=item)
			{
				ans=mid;
				high=mid-1;
			}
			else
				low=mid+1;
				
		}
		return ans;
	}	
	public static boolean isprime(int n)
	{
		for(int i=2;i*i<=n;i++)
		{
			if(n%i==0)
				return false;
		}
		return true;
	}
	public static long fact(long a,long mod)
	{
		long ans=1;
		for(int i=1;i<=a;i++)
		{
			ans*=i;
			ans%=mod;
		}
		return ans%mod;
		
	}
	public static long ncr(long n,long r,long mod)
	{
		long nom=1,dom=1;
		nom=(fact(n,mod))%mod;
		dom=(fact(r,mod)*fact(n-r,mod))%mod;
		return (nom*fastpow(dom,mod-2,mod))%mod;
	}
	public static long gcd(long x, long y)
	{
		if(x==0)
			return y;
		if(y==0)
			return x;
		long r=0, a, b;
		a = (x > y) ? x : y; // a is greater number
		b = (x < y) ? x : y; // b is smaller number
		r = b;
		while(a % b != 0)
		{
			r = a % b;
			a = b;
			b = r;
		}
		return r;
	}
	public static void prime(int n)
	{
		prime[0]=true;
		prime[1]=true;
		for(int i=2;i*i<=n;i++)
		{
			if(prime[i])
				continue;
			for(int j=i;j*i<=n;j++)
			{
				prime[i*j]=true;
			}
		}
	}
	static class InputReader 
	{
		 
		private final InputStream stream;
		private final byte[] buf = new byte[8192];
		private int curChar, snumChars;
		private SpaceCharFilter filter;

		public InputReader(InputStream stream) 
		{
			this.stream = stream;
		}

		public int snext() 
		{
			if (snumChars == -1)
				throw new InputMismatchException();
			if (curChar >= snumChars) 
			{
				curChar = 0;
				try 
				{
					snumChars = stream.read(buf);
				}
				catch (IOException e) 
				{
					throw new InputMismatchException();
				}
				if (snumChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public int nextInt()
		{
			int c = snext();
			while (isSpaceChar(c))
			{
				c = snext();
			}
			int sgn = 1;
			if (c == '-')
			{
				sgn = -1;
				c = snext();
			}
			int res = 0;
			do
			{
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = snext();
			}
			while (!isSpaceChar(c));
			return res * sgn;
		}

		public long nextLong() 
		{
			int c = snext();
			while (isSpaceChar(c)) 
			{
				c = snext();
			}
			int sgn = 1;
			if (c == '-') 
			{
				sgn = -1;
				c = snext();
			}
			long res = 0;
			do
			{
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = snext();
			}
			while (!isSpaceChar(c));
			return res * sgn;
		}

		public int[] nextIntArray(int n) 
		{
			int a[] = new int[n];
			for (int i = 0; i < n; i++) 
			{
				a[i] = nextInt();
			}
			return a;
		}

		public String readString() 
		{
			int c = snext();
			while (isSpaceChar(c)) 
			{
				c = snext();
			}
			StringBuilder res = new StringBuilder();
			do
			{
				res.appendCodePoint(c);
				c = snext();
			}
			while (!isSpaceChar(c));
			return res.toString();
		}

		public String nextLine()
		{
			int c = snext();
			while (isSpaceChar(c))
				c = snext();
			StringBuilder res = new StringBuilder();
			do 
			{
				res.appendCodePoint(c);
				c = snext();
			}
			while (!isEndOfLine(c));
			return res.toString();
		}

		public boolean isSpaceChar(int c) 
		{
			if (filter != null)
				return filter.isSpaceChar(c);
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		private boolean isEndOfLine(int c) 
		{
			return c == '\n' || c == '\r' || c == -1;
		}

		public interface SpaceCharFilter 
		{
			public boolean isSpaceChar(int ch);
		}
	}
	public static long fastpow(long a,long b,long mod)
	{
		long ans=1;
		while(b!=0)
		{
			if(b%2==1)
			{
				ans=(ans*a)%mod;
			}
			a=(a*a)%mod;
			b/=2;
		}
		return ans;
	}
}