#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 1009;
char a[N], b[N];
int n, d[N];
void work() {
    cin >> n;
    cin >> a + 1;
    cin >> b + 1;
    for(int i = 1; i <= n; i ++) {
        if(a[i] == b[i]) d[i] = 0;
        else d[i] = 1;
    }
    vector<pair<int,int>> v;
    for(int i = 1; i <= n; i ++) {
        if(d[i] == 1) {
            int l = i, r = i;
            while(d[r + 1] == 1 && r < n) r ++;
            v.push_back({l, r});
            i = r;
        }
    }
    if(v.size() >= 3) cout << "0" << '\n';
    else if(v.size() == 0) {
        cout << 1ll * n * (n + 1) / 2 << '\n';
    } else if(v.size() == 1) {
        int l = v[0].first;
        int r = v[0].second;
        if(l == r && n == 1) {
            cout << 0 << '\n';
            return;
        }
        long long ans = 2LL * (r - l);
        ans += 2LL * (l - 1);
        ans += 2LL * (n - r);
        cout << ans << '\n';
        return;
    }else if(v.size() == 2){
        cout << 6 << '\n';
    }
}
signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int Case = 1;
    cin >> Case;
    while(Case --) work();
    return 0;
}