func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MAXN = 1005;   int tt, n;   string s, t;   int main() {     cin >> tt;     while (tt--) {       cin >> n >> s >> t;       bool ok = 1;       vector<pair<int, int> > v;       for (int i = 0; i < n; i++) {         if (s[i] == t[i]) continue;         bool naso = 0;         for (int j = i + 1; j < n; j++) {           if (s[i] == s[j]) {             v.push_back({j, i});             swap(s[j], t[i]);             naso = 1;             break;           } else if (s[i] == t[j]) {             v.push_back({j, j});             v.push_back({j, i});             swap(s[j], t[j]);             swap(s[j], t[i]);             naso = 1;             break;           }         }         if (!naso) {           ok = 0;           break;         }       }       if (!ok) {         cout <<  No n ;       } else {         cout <<  Yes n ;         cout << v.size() << endl;         for (auto par : v) {           cout << par.first + 1 <<     << par.second + 1 <<   n ;         }       }     }     return 0;   }   