#include <cstdio>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>
#include <vector>
#include <stack>
using namespace std;
const int MAXN=5e5+10;
int pre[MAXN];
int num[MAXN];
struct node
{int x;int y;int id;
}poi[MAXN];
int cmp1(node a,node b)
{return a.x<b.x;
}
int cmp2(node a,node b)
{return a.y<b.y;
}
int Find(int x)
{int h,tem;h=x;while(x!=pre[x])x=pre[x];while(h!=x){tem=pre[h];pre[h]=x;h=tem;}return x;
}
void join(int x,int y)
{int p=Find(x);int q=Find(y);if(p!=q){pre[p]=q;num[q]=num[p]+num[q];}
}
int main()
{int n;while(scanf("%d",&n)!=EOF){for(int i=0;i<n;i++){pre[i]=i;num[i]=1;}for(int i=0;i<n;i++){scanf("%d%d",&poi[i].x,&poi[i].y);poi[i].id=i;}sort(poi,poi+n,cmp1);for(int i=1;i<n;i++){if(poi[i].x==poi[i-1].x)join(poi[i-1].id,poi[i].id);}sort(poi,poi+n,cmp2);for(int i=1;i<n;i++){if(poi[i].y==poi[i-1].y)join(poi[i-1].id,poi[i].id);}if(num[Find(0)]==n)puts("YES");else puts("NO");}return 0;
}

#include <cstdio>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>
#include <vector>
#include <stack>
using namespace std;
const int MAXN=5e5+10;
int pre[MAXN];
int ans;
int vis[MAXN];
struct node
{int x;int y;int id;
}poi[MAXN];
int cmp1(node a,node b)
{return a.x<b.x;
}
int cmp2(node a,node b)
{return a.y<b.y;
}
int Find(int x)
{int h,tem;h=x;while(x!=pre[x])x=pre[x];while(h!=x){tem=pre[h];pre[h]=x;h=tem;}return x;
}
void join(int x,int y)
{int p=Find(x);int q=Find(y);if(p!=q){pre[p]=q;ans--;}
}
int main()
{int n,x1,x2;while(scanf("%d",&n)!=EOF){memset(vis,0,sizeof(vis));for(int i=1;i<=50000;i++)pre[i]=i;ans=0;for(int i=0;i<n;i++)scanf("%d%d",&poi[i].x,&poi[i].y);for(int i=0;i<n;i++){if(!vis[poi[i].x]){vis[poi[i].x]=1;ans++;}}sort(poi,poi+n,cmp2);for(int i=1;i<n;i++){if(poi[i].y==poi[i-1].y){join(poi[i].x,poi[i-1].x);}}if(ans>1)puts("NO");else puts("YES");}return 0;
}
/*4
1 3
4 5
5 3
4 3
NO
*/