#include <bits/stdc++.h>
using namespace std;
int h, w;
char a[500][500];
int main() {
  while (~scanf("%d %d", &h, &w)) {
    for (int i = 0; i < h; i++) {
      for (int j = 0; j < w; j++) {
        cin >> a[i][j];
      }
    }
    int b = 0;
    int c;
    int d;
    for (int i = 1; i < h - 1; i++) {
      for (int j = 1; j < w - 1; j++) {
        if (a[i][j] == '*' && a[i - 1][j] == '*' && a[i + 1][j] == '*' &&
            a[i][j - 1] == '*' && a[i][j + 1] == '*' &&
            a[i - 1][j - 1] != '*' && a[i - 1][j + 1] != '*' &&
            a[i + 1][j - 1] != '*' && a[i + 1][j + 1] != '*') {
          b++;
          c = i;
          d = j;
        }
      }
    }
    if (b == 1) {
      int e = 0;
      for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
          if (a[i][j] == '*' && i != c && j != d) {
            cout << "NO" << endl;
            e++;
            break;
          } else if (i == c) {
            for (int x = 0; x < w - 1; x++) {
              if (a[i][x] == '*') {
                for (int y = w - 1; y > 0; y--) {
                  if (a[i][y] == '*') {
                    for (int z = x; z <= y; z++) {
                      if (a[i][z] == '.') {
                        cout << "NO" << endl;
                        e++;
                        break;
                      }
                    }
                    break;
                  }
                }
                break;
              }
            }
          } else if (j == d) {
            for (int x = 0; x < h - 1; x++) {
              if (a[x][j] == '*') {
                for (int y = h - 1; y > 0; y--) {
                  if (a[y][j] == '*') {
                    for (int z = x; z <= y; z++) {
                      if (a[z][j] == '.') {
                        cout << "NO" << endl;
                        e++;
                        break;
                      }
                    }
                    break;
                  }
                }
                break;
              }
            }
          }
          if (e != 0) {
            break;
          }
        }
        if (e != 0) {
          break;
        }
      }
      if (e == 0) {
        cout << "YES" << endl;
      }
    } else {
      cout << "NO" << endl;
    }
  }
  return 0;
}
