#include <bits/stdc++.h> using namespace std; int qz(int a){ if(a==4){ cout<<"4,5-->9,10"<<endl; cout<<"8,9-->4,5"<<endl; cout<<"2,3-->8,9"<<endl; cout<<"7,8-->2,3"<<endl; cout<<"1,2-->7,8"<<endl; }else{ cout<<a<<","<<a+1<<"-->"<<2*a+1<<","<<2*a+2<<endl; cout<<2*a-1<<","<<2*a<<"-->"<<a<<","<<a+1<<endl; return qz(a-1); } } int main(){ int n; cin>>n; qz(n); return 0; }