#include <iostream>
using namespace std;
int main(){
  int a,b;cin>>a,b;
  string s;cin>>s;
  bool flg=true;
  if(s.size!=a+b+1)cout<<"No"<<endl,eixt(0);
  if(s[a]!='')cout<<"No"<<endl,eixt(0);
  for(int i=0;i<a+b+1,i++){
  if(i==a)continue;
  if(!isdigit(s[i]))  cout<<"No"<<endl,eixt(0);
    }
  cout<<"Yes"<<endl;
}