#include <bits/stdc++.h>
using namespace std;const int maxn = 1e6 + 5;
int n, t, M, b[maxn], num[110], a[maxn];
int sa[maxn], x[maxn], c[maxn], y[maxn], rk[maxn], height[maxn];
bool vis[maxn];
inline void get_sa(){int m = 2000;for( int i=1; i<=n; i++ ) ++c[x[i]=a[i]];for( int i=1; i<=m; i++ ) c[i] += c[i-1];for( int i=n; i; i-- ) sa[c[x[i]]--] = i;for( int k=1; k<=n; k<<=1 ){int now = 0;for( int i=n-k+1; i<=n; i++ ) y[++now] = i;for( int i=1; i<=n; i++ ) if(sa[i]>k) y[++now] = sa[i]-k;for( int i=0; i<=m; i++ ) c[i] = 0;for( int i=1; i<=n; i++ ) ++c[x[i]];for( int i=1; i<=m; i++ ) c[i] += c[i-1];for( int i=n; i; i-- ) sa[c[x[y[i]]]--] = y[i], y[i]=0;swap(x, y);x[sa[1]] = now = 1;for( int i=2; i<=n; i++ )x[sa[i]] = (y[sa[i]]==y[sa[i-1]] && y[sa[i]+k]==y[sa[i-1]+k]) ? now : ++now;if( now>=n ) return ;m = now;}
}inline void get_height(){int k = 0;for( int i=1; i<=n; i++ ) rk[sa[i]] = i;for( int i=1; i<=n; i++ ){if( rk[i]==1 ) continue;if( k ) k--;int j = sa[rk[i]-1];while( j+k<=n && i+k<=n && a[j+k]==a[i+k] ) k++;height[rk[i]] = k;}
}inline bool check1( int l, int r ){if( r-l+1<t ) return 0;                 //!!!!!!!r-l+1<t  不是r-l+1<nint tmp = 0;memset( vis, 0, sizeof(vis) );for( int i=l; i<=r; i++ )if( !vis[b[sa[i]]] ){tmp ++;vis[b[sa[i]]] = 1;}return tmp == t;
}inline bool check( int x ){int l=1, r=1;while( l<=n ){while( height[r+1]>=x ) r++;if( check1(l, r) ) return 1;l = r+1; r = l;}return 0;
}int main(){freopen("in.txt", "r", stdin);scanf("%d", &t);int len = 0;for( int i=1; i<=t; i++ ){scanf("%d", &M);for( int j=0; j<M; j++ ) scanf("%d", &num[j]);for( int j=1; j<M; j++ ){a[++n] = num[j]-num[j-1];           //进行差分b[n] = i;}a[++n] = 0;         //分隔不同的串b[n] = i;}// for( int i=1; i<=n; i++ ) cout << a[i] << endl;
    get_sa();get_height();// for( int i=1; i<=n; i++ ) cout << height[i] <<endl;int l=1, r=n;int ans=0;while( l<=r ){int mid = l+r>>1;if( check(mid) ) ans = mid, l=mid+1;else r = mid-1;}printf("%d\n", ans+1);return 0;
}