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

#define endl '\n'
#define int long long

void solve() {
    int n; cin >> n;
    string a, b;
    cin >> a >> b;
    if(n == 1 && a != b) {
        cout << 0 << endl;
        return;
    }
    vector<int> c(n + 1);
    for(int i = 0;i < n;i++) {
        c[i + 1] = (a[i] != b[i]);
    }
    int num = 0;
    int l, r;
    for(int i = 1;i <= n;i++) {
        if(c[i]) {
            int j = i;
            l = i;
            while(j + 1 <= n && c[j + 1]) j++;
            r = j;
            num++;
            i = j;
        }
    }
    if(num > 2) {
        cout << 0 << endl;
    }
    else if(num == 0) {
        cout << n * (n + 1) / 2 << endl;
    }
    else if(num == 1) {
        int len = r - l + 1;
        int tmp = (len - 1) * 2;
        tmp += 2 * (l - 1 + n - r);
        cout << tmp << endl;
    }
    else {
        cout << 6 << endl;
    }
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T = 1;
    cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}