#include<bits/stdc++.h> using namespace std; void f(int n){ if(n==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<<n<<","<<n-1<<"-->"<<2*n+1<<","<<2*n+2; cout<<2*n-2<<","<<2*n-1<<"-->"<<n<<","<<n+1; f(n-1); } } int main(){ int n; cin>>n; f(n); return 0; }