#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++;
    else if (s[i] - '0' >= 0 and s[i] - '9' < 10)
      continue;
    else {
      cur++;
    }
  }
  if (cnt == 1 and cur == 0)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
