#include <bits/stdc++.h>
using namespace std;
int X[] = {1, 1, 1, 2};
int Y[] = {0, -1, 1, 0};
char grid[110][110];
int visited[110][110];
int N;
int gcd(int a, int b) { return b ? gcd(b, a % b) : a; }
bool process(int x, int y) {
  bool flag = true;
  for (int i = 0; i < 4; i++) {
    int a = x + X[i];
    int b = y + Y[i];
    if (a >= N or a < 0 or b >= N or b < 0 or grid[a][b] != '#') {
      flag = false;
      break;
    }
  }
  return flag;
}
void mark(int x, int y) {
  visited[x][y]++;
  for (int i = 0; i < 4; i++) {
    int a = x + X[i];
    int b = y + Y[i];
    visited[a][b]++;
  }
}
int main() {
  cin.tie(NULL);
  while (cin >> N) {
    (memset(grid, 0, sizeof(grid)));
    (memset(visited, 0, sizeof(visited)));
    for (int i = 0; i < N; i++) {
      string s;
      cin >> s;
      for (int j = 0; j < N; j++) grid[i][j] = s[j];
    }
    for (int i = 0; i < N; i++) {
      for (int j = 0; j < N; j++) {
        if (!visited[i][j] and grid[i][j] == '#' and process(i, j)) {
          mark(i, j);
        }
      }
    }
    int zero = 0, one = 0;
    bool flag = true;
    for (int i = 0; i < N; i++) {
      for (int j = 0; j < N; j++) {
        if (visited[i][j] == 1) one++;
        if (visited[i][j] == 0) {
          zero++;
          if (grid[i][j] == '#') flag = false;
        }
      }
    }
    if (flag and one + zero == N * N)
      cout << "YES" << endl;
    else
      cout << "NO" << endl;
  }
  return 0;
}
