#include <bits/stdc++.h>

#define int long long

using namespace std;

int combination(int n) {
    if (n < 2) return 0;
    return n * (n - 1) / 2;
}

signed main()
{
    int n;
    cin >> n;
    while(n--)
    {
        int len;
        cin >> len;
        string s1, s2;
        cin >> s1 >> s2;
        if(len == 1)
        {
            if(s1[0] == s2[0]) cout << 1 << endl;
            else cout << 0 << endl;
            continue;
        }
        bool beg = false, en = false;
        int countb = 0;
        int counte = 0;
        bool begin = false;
        bool cut = true;
        vector<int> a, b;
        for(int i = 0; i < len; i++)
        {
            if(s1[i] != s2[i])
            {
                if(cut)
                {
                    countb++;
                    cut = false;
                    a.push_back(i);
                }
            }
            else
            {
                if(!cut)
                {
                    counte++;
                    cut = true;
                    b.push_back(i);
                }
            }
        }
        if(s1[0] != s2[0]) beg = true;
        if(s1[len-1] != s2[len-1])
        {
            en = true;
            b.push_back(len);
        }
        if(countb == 2||counte == 2)
        {
            cout << 6 << endl;
            continue;
        }
        if(countb == counte&&countb == 1&&!beg&&!en)//
        {
            cout << (b[0] - a[0] - 1 + len - (b[0] - a[0])) * 2<< endl;
            continue;
        }
        if(countb == counte&&countb == 1&&beg&&!en)//
        {
            cout << (b[0] - a[0] - 1 + len - b[0]) * 2 << endl;//
            continue;
        }
        if(countb == 1 && counte == 0&&beg&&en)//
        {
            cout << (b[0] - a[0] - 1) * 2 << endl;
            continue;
        }
        if(countb == 1 && counte == 0&&!beg&&en)//
        {
            cout << (b[0] - a[0] - 1 + a[0]) * 2 << endl;
            continue;
        }
        if(countb == counte&&countb == 0)//
        {
            cout << combination(len) + len << endl;
            continue;
        }
    }
    return 0;
}