#include <bits/stdc++.h>
using namespace std;
using namespace std::chrono;
template <typename A>
ostream &operator<<(ostream &cout, vector<A> const &v);
template <typename A, typename B>
ostream &operator<<(ostream &cout, pair<A, B> const &p) {
  return cout << "(" << p.first << ", " << p.second << ")";
}
template <typename A>
ostream &operator<<(ostream &cout, vector<A> const &v) {
  cout << "[";
  for (int i = 0; i < v.size(); i++) {
    if (i) cout << ", ";
    cout << v[i];
  }
  return cout << "]";
}
template <typename A, typename B>
istream &operator>>(istream &cin, pair<A, B> &p) {
  cin >> p.first;
  return cin >> p.second;
}
mt19937 rng(steady_clock::now().time_since_epoch().count());
void usaco(string filename) {
  freopen((filename + ".in").c_str(), "r", stdin);
  freopen((filename + ".out").c_str(), "w", stdout);
}
const long double pi = 3.14159265358979323846;
long long n, m, k, q, l, r, x, y, z;
long long a[1000005];
long long b[1000005];
long long c[1000005];
string second, t;
long long ans = 0;
void solve(int tc) {
  cin >> n >> second >> t;
  vector<long long> ops;
  for (long long i = (n - 1); i >= 0; --i) {
    if (second[0] == t[i]) {
      ops.push_back(1);
      second[0] = '0' + (1 - (second[0] - '0'));
    }
    ops.push_back(i + 1);
    for (long long j = 0; j < (i + 1); ++j)
      second[j] = '0' + (1 - (second[j] - '0'));
    long long v = i + 1;
    for (long long j = 0; j < (v / 2); ++j) swap(second[j], second[v - j - 1]);
  }
  cout << ops.size() << " ";
  {
    for (int ele = 0; ele < (ops.size()); ele++) {
      if (ele) cout << " ";
      cout << ops[ele];
    }
    cout << '\n';
  };
}
int main() {
  { ios_base::sync_with_stdio(false); }
  {
    cin.tie(NULL);
    cout.tie(NULL);
  }
  int tc = 1;
  cin >> tc;
  for (int t = 0; t < tc; t++) solve(t);
}
