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

void solve() {
    int n;cin >> n;
    string a, b;
    cin >> a >> b;
    a = ' ' + a;
    b = ' ' + b;
    if (a == b) {
        cout << n * (n + 1) / 2 << "\n";return;
    }
    int l = 1, r = n;
    while (l <= n) {
        if (a[l] == b[l])l++;
        else break;
    }
    while (r >= 1) {
        if (a[r] == b[r])r--;
        else break;
    }
    if (r < l) {
        cout << 1 << "\n";return;
    }
    int ok = 0;
    for (int i = l;i <= r;i++) {
        if (a[i] == b[i]) {
            ok++;
            int j = i;
            while (a[j] == b[j] and j <= r)j++;
            i = j - 1;
        }
    }
    if (ok == 0) {
        int ans = r - l;
        int s = l - 1;
        ans += s;
        s = n - r;
        ans += s;
        ans *= 2;
        cout << ans << "\n";
        return;
    }
    else if (ok == 1) {
        cout << 6 << "\n";return;
    }
    else {
        int ans = 0;
        cout << ans << "\n";
    }
    // cout << l << " " << r << "\n";
}

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    int T = 1;
#ifdef LOCAL
    freopen("data.in", "r", stdin);
    freopen("data.out", "w", stdout);
#endif
    cin >> T;
    while (T--)
        solve();
    return 0;
}