#include <bits/stdc++.h>
using namespace std;
int s[500][500];
int main() {
  int w, h;
  cin >> h >> w;
  string a[h];
  for (int i = 0; i < h; ++i) {
    cin >> a[i];
  }
  int p1 = -1, p2 = -1;
  for (int i = 1; i < h - 1; ++i) {
    for (int j = 1; j < w - 1; ++j) {
      if (a[i][j] == '*' and a[i][j + 1] == '*' and a[i][j - 1] == '*' and
          a[i + 1][j] == '*' and a[i - 1][j] == '*') {
        p1 = i;
        p2 = j;
        break;
      }
    }
  }
  int i = p1, j = p2;
  while (a[i][j] == '*') {
    s[i][j] = 1;
    j++;
  }
  i = p1, j = p2;
  while (a[i][j] == '*') {
    s[i][j] = 1;
    j--;
  }
  i = p1, j = p2;
  while (a[i][j] == '*') {
    s[i][j] = 1;
    i++;
  }
  i = p1, j = p2;
  while (a[i][j] == '*') {
    s[i][j] = 1;
    i--;
  }
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (a[i][j] == '*' and s[i][j] == 0) {
        cout << "NO\n";
        return 0;
      }
    }
  }
  if (p1 != -1 and p2 != -1) {
    cout << "YES\n";
  } else
    cout << "NO\n";
  return 0;
}
