#include <bits/stdc++.h>
using namespace std;
long long i, j, k;
inline long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
inline bool prime(long long n) {
  long long i;
  for (i = 2; i < sqrt(n) + 1; i++) {
    if (n % i == 0) return false;
  }
  return true;
}
inline bool is_power_of_two(int n) {
  if (n <= 0) return false;
  return (ceil(log2(n)) == floor(log2(n)));
}
inline long long fast_power(int a, int b) {
  long long result = 1;
  while (b > 0) {
    if (b % 2 == 1) result *= a;
    a *= a;
    b /= 2;
  }
  return result;
}
inline vector<long long> all_primes(long long n) {
  vector<bool> marked(n + 1, true);
  marked[0] = false;
  marked[1] = false;
  for (long long i = 2; i <= n; i++) {
    if (marked[i]) {
      for (long long j = i * i; j <= n; j += i) {
        marked[j] = false;
      }
    }
  }
  vector<long long> v;
  for (i = 0; i <= n; i++) {
    if (marked[i]) v.push_back(i);
  }
  return v;
}
void solve() {
  long long n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  for (i = 0; i < n;) {
    if (s[i] == '.')
      i++;
    else {
      for (j = i + 1; j < i + k; j++) {
        if (j < n) {
          if (s[j] == '.') {
            i = j;
            break;
          }
        } else {
          cout << "NO" << endl;
          break;
        }
      }
      if (j == i + k) {
        cout << "NO" << endl;
        break;
      }
    }
  }
  if (i == n) cout << "YES" << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  long long t = 1;
  while (t--) {
    solve();
  }
}
