#include<bits/stdc++.h>
#define int long long
#define endl '\n'
using namespace std;
const int N=2005,mod=27505213;
int n,sum[mod+3],p[N],w[N],ans,id[mod+3];
bool vis[mod+3];
char a[N];
inline int hs(int l,int r){
	return (((p[r]-p[l-1]*w[r-l+1])%mod+mod)%mod+r-l+1)%mod;
}
signed main(){
	//freopen("","r",stdin);
	//freopen("","w",stdout);
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n;
	int b=2511; 
	w[0]=1;
	for(int i=1;i<=2001;i++) w[i]=w[i-1]*b%mod;
	for(int i=1;i<=n;i++){
		cin>>a+1;
		int len=strlen(a+1);
		memset(vis,0,sizeof(vis));
		for(int j=1;j<=len;j++) p[j]=(p[j-1]*b+(a[j]))%mod;
		for(int l=1;l<=len;l++){
			for(int r=l;r<=len;r++){
				if(!vis[hs(l,r)]){
					sum[hs(l,r)]++,id[hs(l,r)]=r-l+1,vis[hs(l,r)]=1;
					if(i==n&&sum[hs(l,r)]==n) ans=max(ans,r-l+1); 
				}
//				cout<<l<<' '<<r<<' '<<hs(l,r)<<endl;
			}
		}
//		cout<<"换行"<<endl; 
	}
	cout<<ans<<endl;
	return 0;
}