#include <bits/stdc++.h>
using namespace std;
const int maxn = 505;
char maze[maxn][maxn];
int main() {
  int w, h;
  cin >> w >> h;
  int sum = 0;
  for (int i = 1; i <= w; ++i)
    for (int j = 1; j <= h; ++j) {
      cin >> maze[i][j];
      if (maze[i][j] == '*') sum++;
    }
  int px = 0, py = 0;
  for (int i = 1; i <= w; ++i) {
    for (int j = 1; j <= h; ++j) {
      if (maze[i - 1][j] == '*' && maze[i + 1][j] == '*' && maze[i][j - 1] &&
          maze[i][j + 1] == '*' && maze[i][j] == '*') {
        py = i, px = j;
        break;
      }
    }
    if (px && py) break;
  }
  for (int j = py - 1; j >= 1; --j) {
    if (maze[j][px] == '*')
      sum--;
    else
      break;
  }
  for (int j = py + 1; j <= w; ++j) {
    if (maze[j][px] == '*')
      sum--;
    else
      break;
  }
  for (int i = px - 1; i >= 1; --i) {
    if (maze[py][i] == '*')
      sum--;
    else
      break;
  }
  for (int i = px + 1; i <= h; ++i) {
    if (maze[py][i] == '*')
      sum--;
    else
      break;
  }
  if (px && py && (sum - 1 == 0))
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
}
