#include <bits/stdc++.h>
const int maxn = 60;
int mtx[maxn][maxn];
int n, m;
bool col_ok(int a, int b) {
  for (int i = 0; i < n; i++) {
    if (mtx[i][a] != mtx[i][b]) return 0;
  }
  return 1;
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++) scanf(" %c", &mtx[i][j]);
  for (int i = 0; i < n; i++) {
    int cmp = -1;
    for (int j = 0; j < m; j++) {
      if (mtx[i][j] == '#') {
        if (cmp == -1) {
          cmp = j;
        } else {
          if (!col_ok(cmp, j)) {
            printf("No\n");
            return 0;
          }
        }
      }
    }
  }
  printf("Yes\n");
  return 0;
}
