#include<bits/stdc++.h>
#define fast() ios::sync_with_stdio(false); cin.tie(nullptr),cout.tie(nullptr);

using namespace std;

void solve(){
	int n; cin >> n;
	string s,t; cin >> s >> t;
	vector<int> v;
	int cnt = 0;
	for(int i = 0;i < n;i ++){
		if(s[i] != t[i]) cnt ++;
		else{
			if(cnt) v.push_back(cnt);
			cnt = 0;
		}
	} if(s[n - 1] != t[n - 1]) v.push_back(cnt);
	int len = v.size();
	if(len == 0){
		int ans = n * (n + 1) / 2;
		cout << ans << endl;
	} else if(len == 1){
		len = v[0];
		int ans = 2 * (len - 1 + n - len);
		cout << ans << endl;
	} else if(len == 2){
		cout << 6 << endl;
	} else{
		cout << 0 << endl;
	}
}

signed main(){
	fast();
	int _t; cin >> _t;
	while(_t --){
		solve();
	} return 0;
}