#include <bits/stdc++.h>
using namespace std;
bool bs[555][555];
int dr[4] = {1, 0, -1, 0};
int dc[4] = {0, 1, 0, -1};
int main() {
  memset(bs, false, sizeof(bs));
  int n, m;
  scanf("%d %d ", &n, &m);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      char ch;
      scanf("%c ", &ch);
      bs[i][j] = (ch == '*');
    }
  }
  bool fd = false;
  int r, c;
  for (int i = 1; i < n - 1; i++) {
    for (int j = 1; j < m - 1; j++) {
      if (!bs[i][j]) continue;
      bool po = true;
      for (int k = 0; k < 4; k++) {
        if (!bs[i + dr[k]][j + dc[k]]) {
          po = false;
          break;
        }
      }
      if (po) {
        fd = true;
        r = i;
        c = j;
        break;
      }
    }
  }
  if (!fd) {
    printf("NO\n");
    return 0;
  }
  for (int i = 0; i < 4; i++) {
    for (int j = 1;; j++) {
      int u = r + dr[i] * j, v = c + dc[i] * j;
      if (u < 0 || u >= n) break;
      if (v < 0 || v >= m) break;
      if (!bs[u][v]) break;
      bs[u][v] = false;
    }
    bs[r][c] = false;
  }
  bool mm = false;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      mm = mm || bs[i][j];
    }
  }
  printf("%s\n", mm ? "NO" : "YES");
}
