#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<map>
using namespace std;
#define ll long long
#define N 2010
char getc(){char c=getchar();while ((c<'A'||c>'Z')&&(c<'a'||c>'z')&&(c<'0'||c>'9')) c=getchar();return c;}
int gcd(int n,int m){return m==0?n:gcd(m,n%m);}
int read()
{int x=0,f=1;char c=getchar();while (c<'0'||c>'9') {if (c=='-') f=-1;c=getchar();}while (c>='0'&&c<='9') x=(x<<1)+(x<<3)+(c^48),c=getchar();return x*f;
}
int n,a[N][N],cnt=1,last=1,len[N],fail[N],u[N],v[N],id[N];
map<int,int> son[N];
void ins(int c,int n)
{int x=++cnt,p=last;last=x;len[x]=len[p]+1;while (!son[p][c]) son[p][c]=x,p=fail[p];if (!p) fail[x]=1;else{int q=son[p][c];if (len[q]==len[p]+1) fail[x]=q;else{int y=++cnt;len[y]=len[p]+1;son[y]=son[q];fail[y]=fail[q],fail[x]=fail[q]=y;while (son[p][c]==q) son[p][c]=y,p=fail[p];}}
}
void run(int n,int *a)
{memset(v,0,sizeof(v));int k=1,l=0;for (int i=1;i<=n;i++){while (!son[k][a[i]]&&k) k=fail[k],l=len[k];if (!k) k=1,l=0;else l++,k=son[k][a[i]],v[k]=max(v[k],l);}for (int i=1;i<=cnt;i++) if (v[id[i]]) v[fail[id[i]]]=len[fail[id[i]]];for (int i=1;i<=cnt;i++) u[i]=min(u[i],v[i]);
}
bool cmp(const int&a,const int&b)
{return len[a]>len[b];
}
int main()
{
#ifndef ONLINE_JUDGEfreopen("bzoj4698.in","r",stdin);freopen("bzoj4698.out","w",stdout);const char LL[]="%I64d\n";
#elseconst char LL[]="%lld\n";
#endifn=read();for (int i=1;i<=n;i++){a[i][0]=read();for (int j=1;j<=a[i][0];j++) a[i][j]=read();for (int j=a[i][0];j>=1;j--) a[i][j]-=a[i][j-1];for (int j=1;j<a[i][0];j++) a[i][j]=a[i][j+1];a[i][0]--;}for (int i=1;i<=a[1][0];i++) ins(a[1][i],i);memset(u,42,sizeof(u));for (int i=1;i<=cnt;i++) id[i]=i;sort(id+1,id+cnt+1,cmp);for (int i=2;i<=n;i++) run(a[i][0],a[i]);int ans=0;for (int i=1;i<=cnt;i++) ans=max(ans,min(len[i],u[i]));cout<<ans+1;return 0;
}