#include<bits/stdc++.h>
using namespace std;
bool cmp(pair<int,int>a,pair<int,int>b)
{
if(a.second==b.second) return a.first<b.first;
return a.second<b.second;
}
int main() {
int n,f=1;
cin>>n;
pair<int,int>p[n+3];
for(int i=0;i<n;i++)
{
int x,y;
cin>>x>>y;
p[i]={x,y};
}
sort(p,p+n,cmp);
map<int,int>m;
for(int i=1;i<n;i++)
{
m[p[i-1].first]++;
m[p[i].second]++;
if(p[i-1].second>p[i].first || m[p[i-1].first]>2 || m[p[i].second]>2)
{
f=0;
break;
}
}
if(f)
cout<<"YES";
else
cout<<"NO";
return 0;
}
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