#include <bits/stdc++.h>
//#pragma GCC optimize("Ofast")
//#pragma GCC target("avx,avx2,fma")
//#pragma GCC optimization ("unroll-loops")

#define int long long
#define pb push_back
#define all(s) s.begin(),s.end()
#define pii pair<int,int>
#define fr first
#define sc second
#define bst ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl "\n"
#define no cout << "NO" << endl;
#define yes cout << "YES" << endl;

using namespace std;

const int N = 5e5 + 10, mod = 1e9 + 7, inf = 1e18 + 7, logn = 23;
const double pi = acos(-1);


void solve() {
	//soln
	int n;
	string a, b;
	cin >> n >> a >> b;
	vector<int> ans;
	for(int i = n - 1; i >= 0; i--) {
		if(a[i] != b[i]) {
			if(a[0] != b[i]) {
				for(int j = 0; j <= i; j++) {
					a[j] = char(1 + '0' - a[j]);
				}
				reverse(a.begin(), a.begin() + i + 1);
				ans.pb(i + 1);
			} else {
				a[0] = char(1 + '0' - a[0]);
				ans.pb(1);
				for(int j = 0; j <= i; j++) {
					a[j] = char(1 + '0' - a[j]);
				}
				reverse(a.begin(), a.begin() + i + 1);
				ans.pb(i + 1);
			}
		}
	}
	cout << ans.size() << endl;
	for(auto it: ans) {
		cout << it << " ";
	}
	cout << endl;
}
main() {
	bst;
	int t = 1;
	cin >> t;
	while(t--) {
		solve();
	}
}