#include <bits/stdc++.h>
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("unroll-loops")
using namespace std;
const double pi =
    3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342;
const int MR = 60;
char s[MR][MR];
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  map<long long, long long> M;
  for (int i = 0; i < (n); ++i) {
    scanf("%s", s[i]);
    long long mask = 0;
    for (int j = 0; j < (m); ++j)
      if (s[i][j] == '#') mask += 1LL << j;
    M[mask] += 1LL << i;
  }
  for (const auto &p1 : M)
    for (const auto &p2 : M)
      if (p1 != p2 && ((p1.first & p2.first) || (p1.second & p2.second))) {
        printf("No\n");
        return 0;
      }
  printf("Yes\n");
  return 0;
}
