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

typedef long long ll;

const ll N = 1000100;
bool a[N];
int main()
{
    ll z;
    cin >> z;
    while(z--)
    {
        ll n;
        cin >> n;
        string s, t;
        cin >> s >> t;
        for(ll i=0; i<n; i++)
            a[i] = (s[i] != t[i]);
        ll segcnt = a[0];
        for(ll i=1; i<n; i++) segcnt += (a[i] && !(a[i-1]));
        if(segcnt > 2)
        {
            cout << 0 << '\n';
            continue;
        }
        ll l, r;
        switch(segcnt)
        {
            case 0:
                cout << n * (n+1) / 2 << '\n';
                break;
            case 1:
                for(l=0; l<n; l++) if(a[l]) break;
                for(r=n-1; r>=0; r--) if(a[r]) break;
                cout << 2*(r-l) << '\n';
                break;
            case 2:
                cout << 6 << '\n';
                break;
        }
    }
    return 0;
}