#include <bits/stdc++.h>
using namespace std;
template <typename T>
T binpow(T a, T n, T m) {
  T r = 1;
  while (n) {
    if (n & 1) r = (r * a) % m;
    a = (a * a) % m;
    n /= 2;
  }
  return r;
}
long long isprime(long long n) {
  if (n == 0 || n == 1) return n;
  if (n % 2 == 0) return (long long)2;
  if (n % 3 == 0)
    return (long long)3;
  else {
    for (long long i = 5; i * i <= n; i += 6) {
      if (n % i == 0) return i;
      if (n % (i + 2) == 0) return (i + 2);
    }
    return n;
  }
}
const long long N = 2e5 + 5;
int main() {
  ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  srand(time(NULL));
  ;
  long long l, r, m, n, i, j, x, y, t;
  cin >> t;
  while (t--) {
    cin >> n;
    string a, b;
    cin >> a >> b;
    string s = a;
    vector<long long> ans;
    for (i = n - 1; i >= 0; --i) {
      if (s[i] == b[i]) continue;
      if (s[0] != b[i]) {
        for (j = 0; j <= i; ++j) {
          if (s[j] == '0')
            s[j] = '1';
          else
            s[j] = '0';
        }
        reverse(s.begin(), s.begin() + i + 1);
        ans.push_back(i + 1);
      } else {
        if (s[0] == '0')
          s[0] = '1';
        else
          s[0] = '0';
        ans.push_back(1);
        for (j = 0; j <= i; ++j) {
          if (s[j] == '0')
            s[j] = '1';
          else
            s[j] = '0';
        }
        reverse(s.begin(), s.begin() + i + 1);
        ans.push_back(i + 1);
      }
    }
    cout << ans.size() << " ";
    for (long long(j) = (0); (j) < (ans.size()); ++(j)) cout << ans[j] << " ";
    cout << ""
         << "\n";
    ;
    ;
  }
}
