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

#define forn(i,a,b) for(int i = a; i < (b); i++)
#define fore(i,a,b) for(int i = a; i <= (b); i++)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define pb push_back
using ll = long long;
using ld = long double;
using ii = pair<int, int>;

void solve()
{
    ll n; cin>>n;
    string s,t; cin>>s>>t;
    forn(i,0,n)
    {
        if (s[i] == t[i]) s[i] = '0';
        else s[i] = '1';
    }
    vector<int> runs;
    int cnt = 0;
    forn(i,0,n)
    {
        if (s[i] == '1')
        {
            cnt++;
        }
        else
        {
            runs.pb(cnt);
            cnt=0;
        }
    }
    if (cnt) runs.pb(cnt);
    if (runs.empty()) {
        cout << n * (n-1) / 2;
        return;
    }
    if (sz(runs) == 1) {
        ll ans = 0;
        ll L=-1,R=-1;
        forn(i,0,n)
        {
            if (s[i] == '1')
            {
                if (L == -1) L = i;
                R = i;
            }
        }
        cout << (runs[0] - 1 + n - runs[0]) * 2 << '\n';
        return;
    }

    cout<<6<<'\n';
}

int main()
{
    cin.tie(0)->sync_with_stdio(0);

    int t; cin>>t;
    forn(i,0,t) solve();
}