#include <bits/stdc++.h>
using namespace std;
long long int c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, t, x, y, z;
long long int mn = 8675435789, mx = -8675868757, PI = 3.14159265359,
              md = 1000000007, aa = 0, bb = 0, cc = 0;
string r, s, u, v, w;
long long int a[250002], b[250002];
map<long long int, long long int> mp, mq;
queue<long long int> qu, qe;
pair<long long int, long long int> pp[30030];
set<string> se, sa;
int main() {
  {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
  }
  cin >> t;
  while (t--) {
    cin >> n >> s >> r;
    cc = 0;
    for (i = n - 1; i >= 0; i--) {
      if (s[i] != r[i]) {
        if (s[0] == r[i]) {
          a[cc] = 1;
          cc++;
          if (s[0] == '1')
            s[0] = '0';
          else
            s[0] = '1';
        }
        a[cc] = i + 1;
        cc++;
        for (j = 0; j < i + 1; j++) {
          if (s[j] == '1')
            s[j] = '0';
          else
            s[j] = '1';
        }
        reverse(s.begin(), s.begin() + i + 1);
      }
    }
    cout << cc << ' ';
    for (i = 0; i < cc; i++) cout << a[i] << ' ';
    cout << endl;
  }
}
