#include<bits/stdc++.h>
#define ll long long
#define enld "\n"
using namespace std;
const int N=1e5+5;

void sol()
{
	int n;
	cin>>n;
	string a,b;
	cin>>a>>b;
	a=" "+a;b=" "+b;
	int cnt=0;
	int num=0;
	
	for(int i=1;i<=n;i++)
	{
		if(a[i]!=b[i])
		{
			int j=i;
			while(j+1<=n&&a[j+1]!=b[j+1])j++;
			cnt++;
			num=max(num,j-i+1);
//			cout<<"*"<<i<<" "<<j<<endl;
			i=j;
		}
	}
	if(cnt==1)
	{
		cout<<(num-1)*2+(n-num)*2<<endl;
	}
	else if(cnt==2)
	{
		cout<<6<<endl;
	}
	else if(cnt==0)
	{
		cout<<n*(n+1)/2<<endl;
	}
	else
	{
		cout<<0<<endl;
	}

}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
    int t=1;
	cin>>t;
	while(t--)
	{
	sol();
	}
	
	
}