func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long n;     cin >> n;     long long a[n + 1][3];     map<long long, long long> m;     for (long long i = 1; i <= n; i++) {       cin >> a[i][0] >> a[i][1] >> a[i][2];     }     vector<pair<double, pair<long long, long long> > > v;     for (long long i = 1; i < n; i++) {       for (long long j = i + 1; j <= n; j++) {         double d =             sqrt(pow(abs(a[i][0] - a[j][0]), 2) + pow(abs(a[i][1] - a[j][1]), 2) +                  pow(abs(a[i][2] - a[j][2]), 2));         v.push_back({d, {i, j}});       }     }     sort(v.begin(), v.end());     long long c = 0;     for (long long i = 0; i < v.size(); i++) {       if (m[(v[i].second).second] == 0 && m[(v[i].second).first] == 0) {         cout << (v[i].second).second <<     << (v[i].second).first << endl;         m[(v[i].second).second]++;         m[(v[i].second).first]++;         c++;       }       if (c == n / 2) break;     }   }   