#include <bits/stdc++.h>
using namespace std;
long long int a, b, s;
int main() {
  string s1;
  cin >> a >> b;
  cin >> s1;
  if (s1[a + 1] != 0) {
    cout << "No" << endl;
    return 0;
  }
  s1[a + 1] = 1;
  for (int i = 1; i <= a + b + 1; i++) {
    if (s1[i] != '0' && s1[i] != '1' && s1[i] != '2' && s1[i] != '3' &&
        s1[i] != '4' && s1[i] != '5' && s1[i] != '6' && s1[i] != '7' &&
        s1[i] != '8' && s1[i] != '9') {
      cout << "No" << endl;
      return 0;
    }
  }
  cout << "Yes" << endl;
  return 0;
}
