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

int n;
string s1, s2;

using ll = long long;
using pll = pair<ll,ll>;
vector<pll> ve;

void solve() {
    ve.clear();
    cin >> n;
    cin >> s1 >> s2;
    for(int i = 0; i < n; i++){
        if(s1[i] != s2[i]){
            int j = i;
            while(j < n && s1[j] != s2[j]){
                j++;
            }
            ve.push_back({i, j});
            i = j;
        }
    }

    if(ve.size() == 0){
        cout << n * (n - 1) / 2 << '\n';
    }else if(ve.size() == 1){
        auto [l, r] = ve[0];
        cout << 2 * ((l) + (n - 1 - r) + (r - l)) << '\n';
    }else if(ve.size() == 2){
        auto [l1, r1] = ve[0];
        auto [l2, r2] = ve[1];
        cout << 6 << '\n';
    }else{
        cout << 0 << '\n';
    }
}
int main() {
    ios :: sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> T;
    while(T--) solve();
    return 0;
}