#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  string str;
  cin >> str;
  bool dp[n];
  dp[0] = true;
  int cur = 0;
  for (int i = 1; i < n; i++) {
    dp[i] = false;
    if (str[i] == '.' && cur >= i - k) {
      dp[i] = true;
      cur = i;
    }
  }
  if (dp[n - 1])
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
}
