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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.StringTokenizer;
import java.util.TreeSet;

public class CF_957_B_MYSTICAL_MOSAIC {

	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int m = sc.nextInt();
		
		char[][] mat = new char[n][m];
		
		for(int i = 0 ; i<n ;i++)
			mat[i] = sc.next().toCharArray();
		boolean [] row = new boolean [n];
		boolean [] column = new boolean [m];
		for(int i = 0 ; i<n ;i++)
		{
			if(row[i]) continue;
			TreeSet<Integer> col = new TreeSet<>();
			
			for(int j = 0 ; j<m ;j++)
				if(mat[i][j] == '#') {
					if(!column[j]) {
						column[j] = true;
						col.add(j);
					}
					else
					{
						System.out.println("No");
						return;
					}
				}
				
			outer :for(int k = i+1 ; k<n ;k++)
			{
				
				for(int j = 0 ; j<m ;j++)
					if(!((mat[k][j] == '#' && col.contains(j)) || 
						(mat[k][j] == '.' && !col.contains(j))))
					 continue outer;
						
				if(!row[k])
					row[k] = true;
				else {
					System.out.println("No");
					return;
				}
				
			}
			
		}
				
		
		System.out.println("YES");
		
	}
	
	static class Scanner {
		StringTokenizer st;
		BufferedReader br;

		public Scanner(InputStream s) {
			br = new BufferedReader(new InputStreamReader(s));
		}

		public String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}

		public int nextInt() throws IOException {
			return Integer.parseInt(next());
		}

		public long nextLong() throws IOException {
			return Long.parseLong(next());
		}

		public String nextLine() throws IOException {
			return br.readLine();
		}

		public double nextDouble() throws IOException {
			String x = next();
			StringBuilder sb = new StringBuilder("0");
			double res = 0, f = 1;
			boolean dec = false, neg = false;
			int start = 0;
			if (x.charAt(0) == '-') {
				neg = true;
				start++;
			}
			for (int i = start; i < x.length(); i++)
				if (x.charAt(i) == '.') {
					res = Long.parseLong(sb.toString());
					sb = new StringBuilder("0");
					dec = true;
				} else {
					sb.append(x.charAt(i));
					if (dec)
						f *= 10;
				}
			res += Long.parseLong(sb.toString()) / f;
			return res * (neg ? -1 : 1);
		}

		public boolean ready() throws IOException {
			return br.ready();
		}

	}

}
