#include <bits/stdc++.h>
using namespace std;
long long power(long long a, long long b, long long c) {
  long long x = 1, y = a;
  while (b > 0) {
    if (b & 1) x = (x * y) % c;
    y = (y * y) % c;
    b /= 2;
  }
  return x % c;
}
const int N = 55;
int n, m;
char s[N][N];
vector<int> row;
bool doit(int x, int y) {
  for (int i = 1; i <= m; ++i) {
    if (s[x][i] != s[y][i]) return 0;
  }
  return 1;
}
bool check() {
  for (int i = 0; i < row.size(); ++i) {
    for (int j = 1; j < row.size(); ++j) {
      if (!doit(row[i], row[j])) return 0;
    }
  }
  return 1;
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; ++i) scanf("%s", s[i] + 1);
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= m; ++j) {
      if (s[i][j] == '#') {
        row.clear();
        for (int k = 1; k <= n; ++k) {
          if (s[k][j] == '#') row.push_back(k);
        }
        if (!check()) {
          printf("No\n");
          return 0;
        }
      }
    }
  }
  printf("Yes\n");
  return 0;
}
