#include <bits/stdc++.h>
#define __LOCAL_DEBUG__
#ifdef __LOCAL_DEBUG__
#define _debug(fmt, ...) fprintf(stderr, "[%s %3d]: " fmt "\n", \
__func__, __LINE__, ##__VA_ARGS__)
#else
# define _debug(...) (void(0))
#endif
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pii;
const ll N = 2E5 + 10, mod = 1E9 + 7, INF = 0x3f3f3f3f3f3f3f3f, inf = 0x3f3f3f3f;
bool chmax(int &a, int b) {
	if (a < b) {
		a = b;
		return 1;
	}
	return 0;
}
bool chmin(ll &a, ll b) {
	if (a > b) {
		a = b;
		return 1;
	}
	return 0;
}

void printv(vector<int> a) {
	for (int i : a) {
		cout << i << ' ';
	}
	cout << '\n';
}
void solve() {
	int n;
	cin >> n;
	string s, t;
	cin >> s >> t;
	int cnt = 0;

	int sum = 0;
	for (int i = 1; i < n; i ++) {
		if (s[i] == t[i] && s[i - 1] != t[i - 1]) {
			cnt ++;
		}
		if (s[i - 1] != t[i - 1]) {
			sum ++;
		}
	}
	if (s[n - 1] != t[n - 1]) {
		cnt ++;
		sum ++;
	}
	if (cnt == 1) {
		ll ex = 0;
		if (sum != n) {
			if (s[0] != t[0] || s[n - 1] != t[n - 1]) {
				ex = 2;
			}
		}
		cout << 1ll * (sum - 1) * 2 + ex << '\n';
	} else if (cnt == 0) {
		cout << 1ll * n * (n + 1) / 2 << '\n';
	} else if (cnt == 2) {
		cout << 6 << '\n';
	} else {
		cout << 0 << '\n';
	}

} 

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