#include<cstdio>

 #include<cstring>

 #include<iostream>

 using namespace std;

 #define maxn 105

 #define maxm 20010

 int n,e;

 bool path[][],flag;

 int first[maxn],next[maxm],v[maxm];

 int color[maxn];

 bool vis[maxn];

 void addedge(int x,int y)

 {

     v[e]=y;

     next[e]=first[x];

     first[x]=e++;

 }

 bool solve(int x,int now,int from)

 {

     int i,k;

     color[x]=now;

     for(i=first[x];i!=-;i=next[i])

     {

         k=v[i];

         if(k!=from)

         {

         if(!color[k])

         {

             if(solve(k,-now,x)==false)return false;

         }

         if(color[k]==color[x])return false;

         }

     }

     vis[x]=true;

     return true;

 }

 int main()

 {

     int L,i;

     while(scanf("%d",&n)!=EOF)

     {

         memset(color,,sizeof(color));

         memset(vis,false,sizeof(vis));

         memset(path,false,sizeof(path));

         for(i=;i<=n;i++)

         {

             while(scanf("%d",&L),L)

                 path[i][L]=true;

         }

         memset(first,-,sizeof(first));

         for(i = ; i < n;i++)

         {

             for(int j=i+;j<=n;j++)

             {

                 if(!path[i][j]||!path[j][i])

                 {

                     addedge(i,j);

                     addedge(j,i);

                 }

             }

         }

         flag=true;

         for(i=;i<=n&&flag==true;i++)

         if(color[i]==){

             vis[i]=true;flag=solve(i,,-);

         }

         if(flag)printf("YES\n");

         else printf("NO\n");

     }

     return ;

 }