#include <bits/stdc++.h>
using namespace std;
char a[55][55];
long long b[55];
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = (1); i <= (n); i++) scanf("%s", a[i] + 1);
  for (int i = (1); i <= (n); i++)
    for (int j = (1); j <= (m); j++)
      if (a[i][j] == '#') b[i] |= (1ll << (j - 1));
  for (int i = (1); i <= (n); i++) {
    for (int j = (1); j <= (n); j++) {
      if (i == j) continue;
      if ((b[i] & b[j]) && (b[i] & b[j]) != b[i]) return !printf("No\n");
    }
  }
  printf("Yes\n");
  return 0;
}
