#include<iostream> using namespace std; int yidong(int k) { if(k==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<<k<<","<<k+1<<"-->"<<2*k+1<<","<<2*k+2<<endl; cout<<2*k-1<<","<<2*k<<"-->"<<k<<","<<k+1<<endl; yidong(k-1); } } int main() { int n; cin>>n; yidong(n); return 0; }