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