#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  string s;
  cin >> a >> b;
  cin >> s;
  for (int i = 0; i <= a + b; i++) {
    if (i == a && s[i] != '_') {
      cout << "No" << endl;
      return 0;
    }
    if (i != a && (s[i] < '0' || s[i] > '9')) {
      cout << "No" << endl;
      return 0;
    }
  }
  cout << "Yes" << endl;
  return 0;
}
