func_code_string: #include <bits/stdc++.h>   using namespace std;   void solve() {     long long n;     cin >> n;     vector<pair<long long, long long>> ans;     long long i = 0;     long long j = 0;     ans.push_back({0, -1});     ans.push_back({-1, 0});     ans.push_back({-1, -1});     for (long long k = 0; k < n; k++) {       ans.push_back({i, j});       ans.push_back({i, j + 1});       ans.push_back({i + 1, j});       i++;       j++;     }     ans.push_back({i, j});     cout << ans.size() << endl;     for (long long i = 0; i < ans.size(); i++)       cout << ans[i].first <<     << ans[i].second << endl;   }   signed main() {     long long t;     t = 1;     while (t--) {       solve();     }   }   