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

int main() {
	// your code goes here
	int t;
	cin>>t;
	while(t--){
	    int n;
	    cin>>n;
	    string s;
	    cin>>s;
	    string s1;
	    int oc=0;
	    for(int i=0;i<n;i++){
	       // cout<<i<<endl;
	        int temp=1-(s[i]-'0');
	        oc+=pow(2,i-1)*temp;
	        s1.push_back(temp+'0');
	    }
	   // cout<<endl;
	   // cout<<s1<<endl;
	   // cout<<oc<<endl;
	}
	return 0;
}