func_code_string: #include <bits/stdc++.h>   using namespace std;   template <class T, class V>   ostream& operator<<(ostream& s, pair<T, V> a) {     s << a.first <<     << a.second;     return s;   }   int main() {     ios::sync_with_stdio(false);     cin.tie(NULL);     long long int T = 1;     cin >> T;     for (long long int qq = 1; qq <= T; qq++) {       long long int n;       string a, b;       cin >> n >> a >> b;       vector<long long int> ans;       long long int f = 0, l = n - 1, r = 0;       for (int i = n - 1; i >= 0; i--) {         if (b[i] -  0  != ((a[l] -  0 ) ^ f)) {           if (a[l] != a[r]) a[r] = (a[r] -  0 ) ^ 1 +  0 , ans.push_back(1);           f ^= 1;           ans.push_back(i + 1);           swap(l, r);         }         if (l > r)           l--;         else           l++;       }       cout << ans.size();       for (auto x : ans) cout <<     << x;       cout << endl;     }   }   