#include <bits/stdc++.h>
using namespace std;
char arr[3 * 100010];
int n, k, dp[3 * 100010];
int dfs(int node) {
  int &ret = dp[node];
  if (ret != -1) return ret;
  if (arr[node] == '#') return ret = 0;
  if (node >= n - 1) return ret = 1;
  for (int i = 1; i <= k; i++) {
    if (arr[node + i] == '.')
      if (dfs(node + i)) return ret = 1;
  }
  return ret = 0;
}
int main() {
  int i, j;
  cin >> n >> k;
  memset(dp, -1, sizeof dp);
  for (i = 0; i < n; i++) cin >> arr[i];
  if (dfs(0))
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
