#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  char a[n][m];
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) cin >> a[i][j];
  }
  vector<int> v1, v2;
  bool f = true, c = 0;
  int row, col;
  for (int i = 1; i < n - 1; i++) {
    for (int j = 1; j < m - 1; j++) {
      if (a[i][j] == '*' && a[i - 1][j] == '*' && a[i][j - 1] == '*' &&
          a[i + 1][j] == '*' && a[i][j + 1] == '*') {
        row = i;
        col = j;
        c++;
      }
    }
  }
  if (c == 1) {
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        if (a[i][j] == '*' && row != i && col != j) f = false;
      }
    }
    if (f == true) {
      for (int i = 0; i < n; i++) {
        if (a[i][col] == '*') v1.push_back(i);
      }
      for (int j = 0; j < m; j++) {
        if (a[row][j] == '*') v2.push_back(j);
      }
      for (int i = 1; i < v1.size(); i++) {
        if (v1[i] - v1[i - 1] != 1) f = false;
      }
      for (int i = 1; i < v2.size(); i++) {
        if (v2[i] - v2[i - 1] != 1) f = false;
      }
    }
  } else
    f = false;
  if (f)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
