#include <bits/stdc++.h>
using namespace std;
const int MXX = 500 + 5;
char cell[MXX][MXX];
int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      cin >> cell[i][j];
    }
  }
  int cnt = 0;
  int ax = -1, bx = -1;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (cell[i][j] == '*' && cell[i + 1][j] == '*' && cell[i - 1][j] == '*' &&
          cell[i][j + 1] == '*' && cell[i][j - 1] == '*') {
        bool flag = true;
        int index1 = -1, index2 = -1, index3 = -1, index4 = -1;
        for (int k = i + 1; k < n; k++) {
          if (cell[k][j] == '*') {
            continue;
          } else {
            index1 = k;
            break;
          }
        }
        if (index1 != -1) {
          for (int k = index1; k < n; k++) {
            if (cell[k][j] == '*') {
              flag = false;
              break;
            }
          }
        }
        for (int k = i - 1; k >= 0; k--) {
          if (cell[k][j] == '*') {
            continue;
          } else {
            index2 = k;
            break;
          }
        }
        if (index2 != -1) {
          for (int k = index2; k >= 0; k--) {
            if (cell[k][j] == '*') {
              flag = false;
              break;
            }
          }
        }
        for (int k = j - 1; k >= 0; k--) {
          if (cell[i][k] == '*') {
            continue;
          } else {
            index3 = k;
            break;
          }
        }
        if (index3 != -1) {
          for (int k = index3; k >= 0; k--) {
            if (cell[i][k] == '*') {
              flag = false;
              break;
            }
          }
        }
        for (int k = j + 1; k < m; k++) {
          if (cell[i][k] == '*') {
            continue;
          } else {
            index4 = k;
            break;
          }
        }
        if (index4 != -1) {
          for (int k = index4; k < m; k++) {
            if (cell[i][k] == '*') {
              flag = false;
              break;
            }
          }
        }
        if (flag) {
          ax = i, bx = j;
          cnt++;
        }
      }
    }
  }
  if (cnt == 1) {
    for (int i = 0; i < n; i++) {
      if (i == ax) continue;
      for (int j = 0; j < m; j++) {
        if (j == bx) continue;
        if (cell[i][j] == '*') {
          cout << "NO" << endl;
          return 0;
        }
      }
    }
    cout << "YES" << endl;
  } else {
    cout << "NO" << endl;
  }
  return 0;
}
