#include <stdio.h>
#include <string.h>

#include <vector>
#include <algorithm>

#define eb emplace_back

using namespace std;

typedef long long LL;
constexpr int N = 1000005;

int n;
char a[N], b[N];
struct Pair {
	int x, y;
	Pair() {}
	Pair(int _x, int _y) : x(_x), y(_y) {}
};
vector<Pair> seq;

int main() {
	int task;
	for (scanf("%d", &task); task--; ) {
		scanf("%d%s%s", &n, a + 1, b + 1);
		seq.clear();
		for (int i = 1, j; (j = i) <= n; i = j + 1) {
			while (j <= n && a[j] != b[j]) {
				++j;
			}
			if (a[i] != b[i]) {
				seq.eb(i, j - 1);
			}
		}
		if (seq.size() >= 3) {
			puts("0");
		} else if (seq.size() == 2) {
			puts("6");
		} else if (seq.size() == 1) {
			auto [l, r] = seq[0];
			printf("%d\n", r - l - 1 + n);
		} else {
			printf("%lld\n", n * (n + 1ll) / 2);
		}
	}
	return 0;
}