#include <bits/stdc++.h>
using namespace std;
char str[510][510];
bool vis[510][510];
int h, w;
void cheak(int x, int y) {
  int i, j;
  i = x, j = y;
  while (j < w && str[i][j] == '*') vis[i][j] = 1, j++;
  i = x, j = y;
  while (j >= 0 && str[i][j] == '*') vis[i][j] = 1, j--;
  i = x, j = y;
  while (i < h && str[i][j] == '*') vis[i][j] = 1, i++;
  i = x, j = y;
  while (i >= 0 && str[i][j] == '*') vis[i][j] = 1, i--;
}
int main() {
  cin >> h >> w;
  for (int i = 0; i < h; i++) scanf("%s", str[i]);
  int flag = 0;
  for (int i = 1; i < h - 1; i++)
    for (int j = 1; j < w - 1; j++) {
      if (flag) break;
      if (str[i][j] == '*') {
        if (str[i + 1][j] == str[i - 1][j])
          if (str[i][j - 1] == str[i][j + 1])
            if (str[i - 1][j] == str[i][j + 1])
              if (str[i - 1][j] == '*') {
                cheak(i, j);
                flag = 1;
              }
      }
    }
  if (flag) {
    for (int i = 0; i < h; i++) {
      for (int j = 0; j <= w; j++)
        if (str[i][j] == '*' && !vis[i][j]) {
          printf("NO\n");
          return 0;
        }
    }
    printf("YES\n");
    return 0;
  }
  printf("NO\n");
  return 0;
}
