#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 50 + 5;
bool visr[MAX_N], visc[MAX_N], vis[MAX_N][MAX_N];
int n, m;
char buf[MAX_N][MAX_N];
inline void dfs(int i, int j) {
  vis[i][j] = visr[i] = visc[j] = true;
  for (register int k = 0; k < n; ++k) {
    if (buf[k][j] == '#' && !vis[k][j]) {
      dfs(k, j);
    }
  }
  for (register int k = 0; k < m; ++k) {
    if (buf[i][k] == '#' && !vis[i][k]) dfs(i, k);
  }
}
inline char readchar() {
  char c = getchar();
  while (c == ' ' || c == '\n') c = getchar();
  return c;
}
void solve() {
  scanf("%d%d", &n, &m);
  for (register int i = 0; i < n; ++i)
    for (register int j = 0; j < m; ++j) buf[i][j] = readchar();
  for (register int i = 0; i < n; ++i)
    for (register int j = 0; j < m; ++j)
      if (buf[i][j] == '#' && !vis[i][j]) {
        memset(visr, 0, sizeof(visr));
        memset(visc, 0, sizeof(visc));
        dfs(i, j);
        for (register int k = 0; k < n; ++k)
          for (register int l = 0; l < m; ++l)
            if (visr[k] && visc[l] && buf[k][l] == '.') {
              puts("NO");
              return;
            }
      }
  puts("YES");
}
int main() {
  solve();
  return 0;
}
