#include <bits/stdc++.h>
using namespace std;
int mysqrt(long long x) {
  int l = 0, r = 1e9 + 1;
  while (r - l > 1) {
    int m = (l + r) / 2;
    if (m * (long long)m <= x)
      l = m;
    else
      r = m;
  }
  return l;
}
mt19937 rnd(1337);
mt19937_64 rndll(12365);
long long AR = 19, BR = 13, CR = 23, XR = 228, YR = 322, MODR = 1e9 + 993;
long long myrand() {
  long long ZR = (XR * AR + YR * BR + CR) % MODR;
  XR = YR;
  YR = ZR;
  return ZR;
}
const int Mod = 1e9 + 7;
int bpow(int x, int y) {
  if (y == 0) return 1;
  if (y == 1) return x;
  int ret = bpow(x, y >> 1);
  ret = (ret * (long long)ret) % Mod;
  if (y & 1) ret = (ret * (long long)x) % Mod;
  return ret;
}
int bdiv(int x, int y) { return (x * (long long)bpow(y, Mod - 2)) % Mod; }
void setmin(int &x, int y) { x = min(x, y); }
void setmax(int &x, int y) { x = max(x, y); }
void setmin(long long &x, long long y) { x = min(x, y); }
void setmax(long long &x, long long y) { x = max(x, y); }
int gcd(int a, int b) { return a ? gcd(b % a, a) : b; }
const long long llinf = 2e18 + 100;
const double eps = 1e-9;
const int maxn = 2e5 + 100, maxw = 1e6 + 100, inf = 2e9 + 100, sq = 300,
          mod = 1e9 + 7, LG = 17;
int n, m;
char a[50][50];
int z(char c) { return c == '#'; }
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> m;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++) cin >> a[i][j];
  for (int i1 = 0; i1 < n; i1++)
    for (int i2 = i1 + 1; i2 < n; i2++)
      for (int j1 = 0; j1 < m; j1++)
        for (int j2 = j1 + 1; j2 < m; j2++)
          if (z(a[i1][j1]) + z(a[i1][j2]) + z(a[i2][j1]) + z(a[i2][j2]) == 3) {
            cout << "No";
            return 0;
          }
  cout << "Yes";
}
