#include <bits/stdc++.h>
const int INF = 0x3f3f3f3f;
const long long LINF = 0x3f3f3f3f3f3f3f3fLL;
const int MOD = int(1e9) + 7;
using namespace std;
using pii = pair<int, int>;
long long gcd(long long x, long long y) {
  if (x < y) swap(x, y);
  long long r = x % y;
  while (r != 0) {
    x = y;
    y = r;
    r = x % y;
  }
  return y;
}
signed main(void) {
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  int a, b;
  string s;
  cin >> a >> b >> s;
  for (int i = 0; i < (s.size()); i++) {
    if (i != a) {
      if (s[i] == '_') {
        cout << "No\n";
        return 0;
      }
    }
  }
  if (s[a] != '_') {
    cout << "No\n";
  } else {
    cout << "Yes\n";
  }
  return 0;
}
