#include<iostream> using namespace std; void qizi(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+1)<<endl; cout<<2*a-1<<","<<2*a<<"-->"<<a<<","<<a+1<<endl; qizi(a - 1); } } int main() { int n; cin >> n; qizi(n); }