#include<bits/stdc++.h>
using namespace std;
int main(){
int A,B;
  cin>>A>>B;
  string S;
  cin>>S;
  bool ans=true;
  for(int i=0;i<N;i++){
  if(i==A){
  if(S.at(i)!='-'){
    ans=false; break;
  }
  }else{
  if(S.at(i)=='-'){
  ans=false; break;
  }
  }
  
  }if(ans)
    cout<<"Yes"<<endl;
  else
    cout<<"No"<<endl;

  
  
  return 0;
}