#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";
    return 0;
  }
  for (int x = 0; x < s.size(); x++) {
    if (s[x] == '-' && x != a) {
      cout << "No";
      return 0;
    }
  }
  cout << "Yes";
  return 0;
}
