#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  string s;
  int a, b;
  cin >> a >> b;
  cin >> s;
  int cnt = 0, cur = 0;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] == '-') cnt++;
  }
  if (cnt == 1)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
