bits/stdc++.hå#include <iostream>
#include <string>
using namespace std;

int main(){

  int A, B;
  cin >> A >> B;
  string S;
  cin >> S;
  bool ans=true;

  for(int i=0; i<S.size(); i++){
    if(i==A){
      if(S[i]!='-') ans = false;
    }else{
      if(!(S[i]>='a' && S[i]<='z')) ans = false;
    }
  }

  if(ans){
    cout << "Yes" << endl;
  }else{
    cout << "No" << endl;
  }

  return 0;
}
