#include <bits/stdc++.h>
const double PI = 3.141592653589793238460;
using namespace std;
long long pows(long long a, long long n, long long m) {
  long long res = 1;
  while (n) {
    if (n % 2 != 0) {
      res = (res * a) % m;
      n--;
    } else {
      a = (a * a) % m;
      n = n / 2;
    }
  }
  return res % m;
}
long long gcd(long long a, long long b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
bool isprime(long long n) {
  if (n == 1) {
    return false;
  }
  for (long long i = 2; i * i <= n; i++) {
    if (n % i == 0) {
      return false;
    }
  }
  return true;
}
bool istrue(string s) {
  int i = 0;
  int j = s.size() - 1;
  while (i < j) {
    if (s[i] == s[j]) {
      i++;
      j--;
    } else {
      return false;
    }
  }
  return true;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    string s, p;
    cin >> s >> p;
    int cnt = 0;
    vector<int> vi;
    cnt = 0;
    for (int i = n - 1; i >= 0; i--) {
      if (s[i] != p[i]) {
        if (s[0] != p[i]) {
          vi.push_back(i + 1);
        } else {
          vi.push_back(1);
          vi.push_back(i + 1);
        }
        for (int j = 0; j <= i; j++) {
          if (s[j] == '0') {
            s[j] = '1';
          } else {
            s[j] = '0';
          }
        }
        reverse(s.begin(), s.end() - cnt);
      }
      cnt++;
    }
    cout << vi.size() << " ";
    for (int res : vi) {
      cout << res << " ";
    }
    cout << endl;
  }
}
