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