#include <bits/stdc++.h>
using namespace std;


int main() {
  int A, B; cin >> A >> B;
  string S; cin >> S;
  int cnt = 0;
  for(int i=0; i<S.size(); i++){
    if(isdigit(S[i])) cnt++;
  }

  if(S[A]=='-' && cnt==A+B) cout << "Yes" << endl;
  else cout << "No" << endl;


  return 0;
}
