#include <bits/stdc++.h>

using i64 = long long;

void solve() {
	int n;
	std::cin >> n;

	std::string s, t;
	std::cin >> s >> t;

	if (s == t) {
		std::cout << 1LL * n * (n + 1) / 2 << "\n";
		return;
	}

	int l = 0;
	while (s[l] == t[l]) {
		l++;
	}
	int r = l;
	while (r < n && s[r] != t[r]) {
		r++;
	}

	int x = r;
	while (x < n && s[x] == t[x]) {
		x++;
	}

	if (x < n) {
		int y = x;
		while (y < n && s[y] != t[y]) {
			y++;
		}
		while (y < n && s[y] == t[y]) {
			y++;
		}
		if (y < n) {
			std::cout << 0 << "\n";
		} else {
			std::cout << 6 << "\n";
		}
		return;
	}

	std::cout << 2 * (n - 1) << "\n";
}

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);

	int T;
	std::cin >> T;

	while (T--) {
		solve();
	}

	return 0;
}