#include <bits/stdc++.h>
int N, K, m;
char S[300009];
int ma[300009];
int main() {
  scanf("%d %d", &N, &K);
  scanf("%s", S);
  for (int h = 0; h < N; h++) {
    if (S[h] == '.') m = h;
    ma[h] = m;
  }
  m = ma[(N - 1 < K ? N - 1 : K)];
  for (int h = 1; h < N; h++)
    if (S[h] == '.' && m >= h) m = ma[(N - 1 < h + K ? N - 1 : h + K)];
  if (m == N - 1)
    printf("YES");
  else
    printf("NO");
}
