#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
long long mod = 1000000000 + 7;
vector<vector<int> > g;
long long pow(long long a, long long b, long long m) {
  stack<int> k;
  int j = 128;
  int l = 1;
  int an = 1;
  while (b) {
    if (b >= j) {
      k.push(j);
      b -= j;
    }
    j /= 2;
  }
  while (!k.empty()) {
    if (k.top() == l) {
      an = (an * a) % mod;
      k.pop();
    }
    a = (a * a) % mod;
    l *= 2;
  }
  return an;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  long n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  int o = 0;
  while (1) {
    int f = 0;
    for (int i = k; i > 0; --i) {
      if (o + i < n && s[o + i] == '.') {
        f = 1;
        o += i;
        break;
      }
    }
    if (!f) {
      cout << "NO" << endl;
      return 0;
    }
    if (o == n - 1) {
      break;
    }
  }
  cout << "YES" << endl;
  return 0;
}
