#include <bits/stdc++.h>
using namespace std;
const long long int INF = 2000000000000000000;
long long int MOD(long long int a, long long int b) {
  if (a > b)
    return a - b;
  else
    return b - a;
}
long long int max3(long long int a, long long int b, long long int c) {
  return max(c, max(a, b));
}
long long int min3(long long int a, long long int b, long long int c) {
  return min(a, min(b, c));
}
long long int power(long long int x, long long int y) {
  long long int res = 1;
  while (y > 0) {
    if (y & 1) res = (res * x) % 1000000007;
    y = y >> 1;
    x = (x * x) % 1000000007;
  }
  return res;
}
long long int logg(long long int a) {
  long long int x = 0;
  while (a > 1) {
    x++;
    a /= 2;
  }
  return x;
}
long long int gcd(long long int a, long long int b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
int main() {
  int n, m;
  cin >> n >> m;
  vector<string> grid;
  grid.resize(n);
  for (int i = 0; i < n; i++) {
    cin >> grid[i];
  }
  vector<int> columns;
  columns.resize(n, 0);
  vector<int> rows;
  rows.resize(m, 0);
  for (int i = 0; i < n; i++) {
    vector<int> cnt;
    for (int j = 0; j < m; j++) {
      if (grid[i][j] == '#') {
        cnt.push_back(j);
      }
    }
    if (!cnt.empty()) {
      vector<int> b;
      for (int j = 0; j < n; j++) {
        if (grid[j][cnt[0]] == '#') {
          b.push_back(j);
        }
      }
      sort(b.begin(), b.end());
      sort(cnt.begin(), cnt.end());
      for (int j = 0; j < cnt.size(); j++) {
        int num = 0;
        for (int i = 0; i < n; i++) {
          if (grid[i][cnt[j]] == '#' &&
              binary_search(b.begin(), b.end(), i) == false) {
            cout << "NO";
            return 0;
          } else {
            if (grid[i][cnt[j]] == '#') {
              num++;
            }
          }
        }
        if (num != b.size()) {
          cout << "NO";
          return 0;
        }
      }
      for (int i = 0; i < b.size(); i++) {
        int num = 0;
        for (int j = 0; j < m; j++) {
          if (grid[b[i]][j] == '#' &&
              binary_search(cnt.begin(), cnt.end(), j) == false) {
            cout << "NO";
            return 0;
          } else {
            if (grid[b[i]][j] == '#') {
              num++;
            }
          }
        }
        if (num != cnt.size()) {
          cout << "NO";
          return 0;
        }
      }
    }
  }
  cout << "YES";
  return 0;
}
