#include <bits/stdc++.h> using namespace std; int main() { int n,a[100000],b[100000],i,j; cin>>n; for(i=1;i<=n;i++){ cin>>a[i]; cin>>b[i]; } sort(a+1,a+n+1); sort(b+1,b+n+1); for(i=1;i<=n;i++){ cout<<a[i]<<" "; cout<<b[i]<<endl; } return 0; }