#include<bits/stdc++.h>
using namespace std;
inline void read(int &res){
	res=0;
	int f=1;
	char c=getchar();
	while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
	while(c>='0'&&c<='9')res=(res<<1)+(res<<3)+c-48,c=getchar();
	res*=f;
}
int n;
map<unsigned long long,int>vis;
int f[100005][2];
unsigned long long base=19260817,cf[100005];
struct node{
	unsigned long long num;
	int len;
}a[100005];
bool cmp(node x,node y){
	return x.len<y.len;
}
int ans;
int main()
{
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	cf[0]=1;
	for(int i=1;i<=100000;i++)cf[i]=cf[i-1]*base;
	read(n);
	for(int i=1;i<=n;i++){
		string s;
		cin>>s;
		a[i].len=s.length();
		for(int j=0;j<a[i].len;j++){
			a[i].num=a[i].num*base+s[j];
		}
	}
	sort(a+1,a+n+1,cmp);
	for(int i=1;i<=n;i++)vis[a[i].num]=i;
	for(int i=1;i<=n;i++){
		if(a[i].len==1)f[i][0]=f[i][1]=1;
		if(f[i][0]&&f[i][1]){
			ans=a[i].len;
			for(unsigned long long j='a';j<='z';j++){
				unsigned long long y=a[i].num*base+j;
				if(vis[y]){
					f[vis[y]][0]=1;
				}
				y=j*cf[a[i].len]+a[i].num;
				if(vis[y]){
					f[vis[y]][1]=1;
				}
			}
		}
	}
	cout<<ans;
	return 0;
}