#include <algorithm>

#include <iostream>

#include <cstdlib>

#include <cstring>

#include <cstdio>

#include <cmath>

using namespace std;

const int N=20005;

int s[N],n=0,k,tmp[N],sa[N],rk[N],high[N],color[N],m,l[6];char S[6][2005];

bool comp(int i,int j){

    if(rk[i]!=rk[j])return rk[i]<rk[j];

    int ri=i+k<=n?rk[i+k]:-1;

    int rj=j+k<=n?rk[j+k]:-1;

    return ri<rj;

}

void Getsa(){

    for(int i=1;i<=n;i++){

        sa[i]=i;rk[i]=s[i];

    }

    for(k=1;k<=n;k<<=1){

        sort(sa+1,sa+n+1,comp);

        for(int i=1;i<=n;i++)tmp[sa[i]]=tmp[sa[i-1]]+comp(sa[i-1],sa[i]);

        for(int i=1;i<=n;i++)rk[i]=tmp[i];

    }

}

void Gethight(){

    int j,h=0;

    for(int i=1;i<=n;i++){

        j=sa[rk[i]-1];

        if(h)h--;

        for(;j+h<=n && i+h<=n;h++)if(s[i+h]!=s[j+h])break;

        high[rk[i]-1]=h;

    }

}

void prework(int m){

    int p=0;

    for(int i=1;i<=m;i++){

        for(int j=1;j<=l[i];j++)

            p++,color[p]=i;

        p++;

    }

}

bool d[8];

bool check(int lim){

    int p,ret;

    for(int i=1;i<n;i++){

        if(high[i]>=lim){

            p=i;

            while(p<n && high[p+1]>=lim)p++;p++;

            for(int j=1;j<=m;j++)d[j]=false;

            for(int j=i;j<=p;j++)d[color[sa[j]]]=true;

            ret=p;p=1;

            while(p<=m && d[p])p++;

            if(p==m+1)return true;

            i=ret;

        }

    }

    return false;

}

int main()

{

    freopen("pow.in","r",stdin);

    freopen("pow.out","w",stdout);

    int r=2e8;

    scanf("%d",&m);

    for(int i=1;i<=m;i++){

        scanf("%s",S[i]);

        l[i]=strlen(S[i]);

        if(l[i]<r)r=l[i];

        for(int j=0;j<l[i];j++)s[++n]=S[i][j];

        s[++n]=i;

    }

    Getsa();Gethight();prework(m);

    int l=0,mid,ans;

    while(l<=r){

        mid=(l+r)>>1;

        if(check(mid))ans=mid,l=mid+1;

        else r=mid-1;

    }

    printf("%d\n",ans);

    return 0;

}