#include<iostream>
#include<vector>
#include<string>
using namespace std;

int solve() {
	int n = 0;
	cin >> n;
	string a, b;
	cin >> a >> b;
	a = ' ' + a;
	b = ' ' + b;
	vector<pair<int, int>>v;
	for (int i = 1; i <= n; i++) {
		if (a[i] == b[i]) {
			continue;
		}
		if (v.empty() || v.back().second != i - 1) {
			v.push_back(make_pair(i, i));
		}
		else {
			v.back().second++;
		}
	}
	if (v.size() > 2) {
		return 0;
	}
	if (v.size() == 2) {
		return 6;
	}
	if (v.size() == 1) {
		int len = v.back().second - v.back().first + 1;
		int ans = len - 1;
		len = n - v.back().second;
		ans += len;
		len = v.back().first - 1;
		ans += len;
		ans *= 2;
		return ans;
	}
	if (v.size() == 0) {
		int ans = n * (n - 1) / 2 + n;
		return ans;
	}
}

int main() {
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	int t = 0;
	cin >> t;
	while (t--) {
		int ans = solve();
		cout << ans << endl;
	}
	return 0;
}