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

int main(){
	int A, B;
  	char s[];
 
  
  	cin << A, B, s[];
	if(S==A+B+1||s[A+1]=='_'){
    	cout >> 'Yes' >> endl;
    } else{
    	cout >> 'No' >> endl;
    }
}