#include <bits/stdc++.h>
using namespace std;
int h, w, i, j, x, c, r;
string s[600];
int main() {
  for (cin >> h >> w; i < h; i++)
    for (cin >> s[i], j = 0; j < w; j++) r += s[i][j] == '*';
  for (i = 1; i < h - 1; i++)
    for (j = 1; j < w - 1; j++)
      if (s[i][j] == '*' && s[i][j - 1] == '*' && s[i][j + 1] == '*' &&
          s[i - 1][j] == '*' && s[i + 1][j] == '*') {
        for (x = i; x < h && s[x][j] == '*'; x++) c++;
        for (x = i - 1; x >= 0 && s[x][j] == '*'; x--) c++;
        for (x = j + 1; x < w && s[i][x] == '*'; x++) c++;
        for (x = j - 1; x >= 0 && s[i][x] == '*'; x--) c++;
        return cout << (r == c ? "YES" : "NO"), 0;
      }
  cout << "NO";
}
