#include<iostream>
using namespace std;

int main(){
	int a,b;
	string s;
	cin>>a>>b>>s;
	bool check=true;
	for(int i=0;i<a+b+1;i++){
		if(i==a)continue;
		int num=(int)(s[i]-'0');
		if(0>num || num>9){
			check=false;
			break;
		}
	}
	if(s[a]=='-' &&check)cout<<"Yes"<<endl;
	else cout<<"No"<<endl;
}