#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=110005;
int n;
string a,b;
void solve(){
	cin>>n;
	cin>>a>>b;
	int cnt=0;int f=0;
	vector<int> nums;int l=0;
	for(int i=0;i<n;i++){
		if(!f&&(int)(a[i]-'0')+(int)(b[i]-'0')==1){
			f=1;l++;
		}
		else if(f&&(int)(a[i]-'0')+(int)(b[i]-'0')==1){
			l++;
		}
		if(f&&(int)(a[i]-'0')+(int)(b[i]-'0')!=1){
			f=0;cnt++;
			nums.emplace_back(l);l=0;
		}
	}
	if(f&&(int)(a[n-1]-'0')+(int)(b[n-1]-'0')==1){
		nums.emplace_back(l);
	}
	if(nums.size()>2){
		cout<<0<<endl;
		return;
	}
	if(nums.size()==1){
		cout<<2*(n-nums.size())+2*(nums.size()-1)<<endl;
	}
	else if(nums.size()==2){
		cout<<6<<endl;
	}
	return;
}
signed main() {
	ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	//freopen("in.txt","r",stdin);
	//freopen("out.txt","w",stdout);
	int t=1;
	cin>>t;
	while(t--){
		solve();
	}
    return 0;
}