#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  cin >> a >> b;
  string s;
  cin >> s;
  if (s.size() != (a + b + 1)) {
    cout << "NO" << endl;
    return 0;
  }
  for (int i = 0; i < s.size(); i++) {
    if (i != a) {
      if (!(s[i] >= '0' && s[i] <= '9')) {
        cout << "NO" << endl;
        return 0;
      }
    } else if (s[i] != '-') {
      cout << "NO" << endl;
      return 0;
    }
  }
  cout << "Yes" << endl;
  return 0;
}
