#include <bits/stdc++.h>

using namespace std;

int main()
{
	int T, n, ans = 0;
	cin >> T;
	while (T--) {
		string s, t;
		ans = 0;
		cin >> n >> s >> t;
		for (int i = 0; i < n; ) {
			for (int j = t.find(s[i]); j < n; j++, i++) {
				if (s[i] != t[j]) {
					ans++;
					break;
				}
			}
		}
		cout << ans << endl;
	}

	return 0;
}