func_code_string: #include <bits/stdc++.h>   using namespace std;   template <class T>   typename T::value_type arr_sum(const T& v, int n) {     typename T::value_type sum = 0;     for (int i = 0; i < n; ++i) sum += v[i];     return sum;   }   struct Sync_stdio {     Sync_stdio() {       cin.tie(NULL);       ios_base::sync_with_stdio(false);     }   } _sync_stdio;   int main() {     int n, m;     cin >> n >> m;     vector<int> left;     vector<int> right(n);     for (int i = 0; i < n; ++i) {       int t;       cin >> t;       left.push_back(t);     }     sort(left.begin(), left.end());     for (int i = 0, j = n / 2; i < n; ++i, j = (j + 1) % n) {       right[i] = left[j];     }     int res = 0;     for (int i = 0; i < n; ++i) {       if (left[i] == right[i]) {         ++res;       }     }     cout << n - res <<   n ;     for (int i = 0; i < n; ++i) {       cout << left[i] <<     << right[i] <<   n ;     }   }   