#include <bits/stdc++.h>
using namespace std;
const int inf = 0x3f3f3f3f;
inline long long read() {
  long long x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = (x << 1) + (x << 3) + (ch ^ 48);
    ch = getchar();
  }
  return x * f;
}
long long die = 0;
const double eps = 1e-8;
const long long mod = 1e9 + 7;
const long long N1 = 1e6 + 5;
const long long N2 = 1e5 + 5;
long long n, m;
char G[505][505];
long long dx[4] = {0, 0, 1, -1};
long long dy[4] = {1, -1, 0, 0};
void sol1() {
  long long cnt = 0;
  for (long long i = (1); i <= (n); i++)
    for (long long j = (1); j <= (m); j++)
      if (G[i][j] == '*') cnt++;
  for (long long i = (2); i <= (n - 1); i++)
    for (long long j = (2); j <= (m - 1); j++) {
      if (G[i][j] == '*') {
        long long tot = 1;
        bool fg = 1;
        for (long long k = (0); k <= (3); k++) {
          long long x = i, y = j;
          bool f = 0;
          while (1) {
            long long tx = x + dx[k];
            long long ty = y + dy[k];
            if (tx < 1 || ty < 1 || tx > n || ty > m) break;
            if (G[tx][ty] == '*') {
              tot++, x = tx, y = ty;
              f = 1;
            } else {
              break;
            }
          }
          if (!f) fg = 0;
        }
        if (fg && tot == cnt) {
          cout << "YES";
          return;
        }
      }
    }
  cout << "NO";
}
void rd() {
  n = read(), m = read();
  for (long long i = (1); i <= (n); i++) scanf("%s", G[i] + 1);
  sol1();
}
signed main() { rd(); }
