#include <bits/stdc++.h>   using namespace std;   const long long MOD = 1000000007;   int dx[] = {1, 1, 0, -1, -1, -1, 0, 1};   int dy[] = {0, 1, 1, 1, 0, -1, -1, -1};   long long POW(long long x, long long y) {     long long ans = 1;     long long base = x;     while (y) {       if (y & 1) {         ans *= base;       }       base = base * base;       y = y >> 1;     }     return ans;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     ;     long long n, i, j, k, t, temp, tc;     cin >> tc;     while (tc--) {       cin >> n;       string a, b;       vector<long long> ans;       cin >> a >> b;       for (i = n - 1; i >= 0; i--) {         if (a[i] != b[i]) {           if (a[0] != b[i]) {             ans.push_back(i);           } else {             ans.push_back(0);             if (b[i] ==  1 ) {               a[0] =  0 ;             } else {               a[0] =  1 ;             }             ans.push_back(i);           }           for (j = 0; j <= i; j++) {             if (a[j] ==  1 ) {               a[j] =  0 ;             } else {               a[j] =  1 ;             }           }           long long lb = 0, ub = i;           while (lb < ub) {             auto ch = a[lb];             a[lb] = a[ub];             a[ub] = ch;             lb++;             ub--;           }         }       }       cout << ans.size() <<    ;       for (auto x : ans) {         cout << x + 1 <<    ;       }       cout << endl;     }     return 0;   }   