#include <bits/stdc++.h>

using namespace std;
using ll = long long;

ll solve() {
    int n; cin >> n;
    string s, t; cin >> s >> t;
    vector<pair<int, int>> diff;
    for (int i = 0; i < n; ++i) {
        if (s[i] != t[i]) {
            if (i == 0 || s[i-1] == t[i-1]) {
                diff.emplace_back(i, i);
            } else {
                diff.back().second = i;
            }
        }
    }
    if (diff.size() > 2) return 0;
    else if (diff.size() == 2) return 6;
    else if (diff.size() == 1) {
        return 2 * (n - 1);
    } else {
        return (ll)n * (n + 1) / 2;
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t; cin >> t;
    while (t--) {
        cout << solve() << "\n";
    }
}