func_code_string: #include <bits/stdc++.h>   using namespace std;   void debug_out() { cerr <<   n ; }   template <typename H, typename... T>   void debug_out(H h, T... t) {     cerr <<     << (h);     debug_out(t...);   }   int n;   string a, b;   char flip(char ch) { return (char)( 0  + ( 1  - ch)); }   char ch(int i, int cnt) { return (char)( 0  + ((a[i] -  0  + cnt) % 2)); }   void solve() {     cin >> n >> a >> b;     vector<int> res;     int first = 0;     int last = n - 1;     int cnt = 0;     for (int i = n - 1; i >= 0; i--) {       if (ch(last, cnt) != b[i]) {         if (ch(first, cnt) == b[i]) {           res.push_back(1);           a[first] = flip(a[first]);         }         if (i or ch(first, cnt) != b[i]) {           res.push_back(i + 1);           cnt++;           swap(first, last);         }       }       if (cnt % 2) {         last++;       } else {         last--;       }     }     cout << res.size();     for (auto i : res) cout <<     << i;     cout <<   n ;   }   int main() {     int t;     cin >> t;     while (t--) {       solve();     }     return 0;   }   