#include <bits/stdc++.h>
using namespace std;
const int maxn = 300005;
bool f[maxn];
int n, k;
string s;
int main() {
  if (0) {
    freopen("a.inp", "r", stdin);
    freopen("a.out", "w", stdout);
  };
  scanf("%d%d\n", &n, &k);
  getline(cin, s);
  int step = k;
  for (int i = 2; i <= n; i++) {
    step--;
    if (s[i - 1] == '#') continue;
    if (step >= 0)
      step = k;
    else {
      puts("NO");
      return 0;
    }
  }
  puts("YES");
}
