#include <bits/stdc++.h>
using namespace std;
int h, w, i, j;
char mp[501][510];
int rx = -1, ry = -1, res;
int main() {
  scanf("%d %d", &h, &w);
  for (i = 0; i < h; i++) {
    scanf("%s", mp[i]);
  }
  for (i = 1; i < h - 1; i++) {
    for (j = 1; j < w - 1; j++) {
      if (mp[i][j] != '*') continue;
      res = !!(mp[i - 1][j] == '*');
      res += !!(mp[i + 1][j] == '*');
      res += !!(mp[i][j - 1] == '*');
      res += !!(mp[i][j + 1] == '*');
      if (res == 4) {
        rx = i;
        ry = j;
        break;
      }
    }
    if (rx != -1) break;
  }
  if (rx == -1) {
    printf("NO\n");
    return 0;
  }
  mp[rx][ry] = '.';
  i = rx + 1;
  while (i < h && mp[i][ry] == '*') mp[i++][ry] = '.';
  i = rx - 1;
  while (i >= 0 && mp[i][ry] == '*') mp[i--][ry] = '.';
  i = ry + 1;
  while (i < w && mp[rx][i] == '*') mp[rx][i++] = '.';
  i = ry - 1;
  while (i >= 0 && mp[rx][i] == '*') mp[rx][i--] = '.';
  for (i = 0; i < h; i++) {
    for (j = 0; j < w; j++) {
      if (mp[i][j] != '.') {
        printf("NO\n");
        return 0;
      }
    }
  }
  printf("YES\n");
  return 0;
}
