This question can be simulated directly with an array
#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include<algorithm>
using namespace std;
int num[500001],num1[500001];
int main(){
int n;
while((cin>>n) && n){
int flag = 1;
for(int i= 0;i<n;i++){
cin>>num[i]>>num1[i];
}
sort(num,num + n);
sort(num1,num1 + n);
for(int i = 0;i < n;i++){
if(num[i] != num1[i]){
flag = 0;
break;
}
}
if(flag)
cout<<"YES"<<endl;
else
cout<<"NO"<<endl;
}
return 0;
}