#include <bits/stdc++.h>
using namespace std;
int x[100], a, b, ans = 0;
int main() {
  string s;
  cin >> a >> b >> s;
  if (a + b + 1 == s.size() && s[a] == '-') {
    for (int i = 0; i < s.size(); i++) {
      if (s[i] == '-')
        x[i] = 0;
      else
        x[i] = s[i];
    }
    for (int j = 0; j < s.size(); j++) {
      ans += x[j];
    }
    if (ans > 0)
      cout << "Yes" << endl;
    else
      cout << "No" << endl;
  } else
    cout << "No" << endl;
  system("pause");
  return 0;
}
