#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

const int MAXN = 1e6 + 10;
char str1[MAXN], str2[MAXN];

int main() {
	int t;
	scanf("%d", &t);
	for (int u = 1; u <= t; u++) {
		int n;
		scanf("%d", &n);
		scanf("%s", str1 + 1);
		scanf("%s", str2 + 1);
		int s1 = -1, e1 = -1, s2 = -1, e2 = -1;
		bool flag = true;
		for (int i = 1; i <= n; i++) {
			if (str1[i] != str2[i]) {
				if (s1 == -1) {
					s1 = i;
				} 
				if (s1 != -1 && e1 != -1 && s2 == -1) {
					s2 = i;
				} 
				if (s1 != -1 && e1 != -1 && s2 != -1 && e2 != -1) {
					flag = false;
					break;
				}
			} else {
				if (s1 != -1 && e1 == -1 && s2 == -1)
					e1 = i - 1;
				if (s1 != -1 && e1 != -1 && s2 != -1 && e2 == -1)
					e2 = i - 1;
			}
		}
		if (s1 != -1 && e1 == -1 && s2 == -1) e1 = n;
		if (s1 != -1 && e1 != -1 && s2 != -1 && e2 == -1) e2 = n;
		//cout << s1 << " " << e1 << " " << s2 << " " << e2 << endl; 
		if (s1 == -1) {
			printf("%lld\n", n * (n + 1) / 2);
		} else if (s2 == -1) {
			printf("%lld\n", 2 * (e1 - s1 + s1 - 1 + n - e1));
		} else if (flag) {
			printf("6\n");
		} else 
			printf("0\n");
	}
	return 0;
}