#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:256000000")
using namespace std;
using ll = long long;
void solve() {
  int n, m;
  scanf("%d%d\n", &n, &m);
  vector<ll> xs(n);
  for (int i = 0; i < n; ++i) {
    string s;
    getline(cin, s);
    ll x = 0;
    for (int j = 0; j < m; ++j) {
      x <<= 1;
      if (s[j] == '#') x |= 1;
    }
    for (int j = 0; j < i; ++j) {
      if ((xs[j] & x) && xs[j] != x) {
        printf("No");
        return;
      }
    }
    xs[i] = x;
  }
  printf("Yes");
}
int main() {
  solve();
  return 0;
}
