func_code_string: #include <bits/stdc++.h>   using namespace std;   using pii = pair<int, int>;   int n;   vector<int> a[200];   int main() {     ios_base::sync_with_stdio(false), cin.tie(0), cout << fixed;     cin >> n;     int k = (1 + sqrt(1 + 8 * n)) / 2, x = 1;     cout << k << endl;     for (int i = 1; i <= k; i++) {       for (int j = i + 1; j <= k; j++) {         a[i].push_back(x);         a[j].push_back(x);         x++;       }     }     for (int i = 1; i <= k; i++) {       int m = a[i].size();       for (int j = 0; j < m; j++) {         cout << a[i][j] << (j == m - 1 ?   n  :    );       }     }     return 0;   }   