/*
ID: espr1t
TASK: 
KEYWORDS: 
*/

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#include <string>

using namespace std;
FILE *in; FILE *out;

const int MAX = 1024;

int n, m;
char a[MAX][MAX];

int main(void) {
	in = stdin; out = stdout;
	in = fopen("barcode.in", "rt"); out = fopen("barcode.out", "wt");
	
	fscanf(in, "%d %d", &n, &m);
	for (int i = 0; i < n; i++)
	    fscanf(in, "%s", a[i]);
	
	for (int i = 0; i < m; i++) {
	    if (!isdigit(a[n - 1][i])) {
	        fprintf(out, "NO\n");
	        return 0;
        }
    }
    n--;
    
    for (int i = 0; i < n; i++) {
        for (int c = 0; c < m; c++) {
            if (isdigit(a[i][c])) {
                fprintf(out, "NO\n");
                return 0;
            }
        }
    }
    
    for (int i = 0; i < m; i++) {
        if (a[0][i] == '.') {
            for (int c = 0; c < n; c++) {
                if (a[c][i] != '.') {
                    fprintf(out, "NO\n");
                    return 0;
                }
            }
        } else {
            for (int c = 0; c < n; c++) {
                if (a[c][i] != '#') {
                    fprintf(out, "NO\n");
                    return 0;
                }
            }
        }
    }

    fprintf(out, "YES\n");
	return 0;
}