/*
    BZOJ 1174: [Balkan2007]Toponyms

    Trie树
    
    将每个字符串插入Trie树中
    
    定义Trie树上点的权值为 以当前点为根的子树中串的数量乘以当前点的深度
    
    则答案即为最大的点权。。 
    不过这题卡空间
　　 先用指针写了写，果然RE（就是超空间）
    于是就改成前向星了

*/
#include <cstdio>

void read (int &now)
{
    register char word = getchar ();
    for (now = 0; word < ‘0‘ || word > ‘9‘; word = getchar ());
    for (; word >= ‘0‘ && word <= ‘9‘; now = now * 10 + word - ‘0‘, word = getchar ());
}

#define Max 5000010

int __next[Max];
int __to[Max];
int edge_list[Max];
int Edge_Count = 1;
char __key[Max];

int value[Max];

inline int max (int a, int b)
{
    return a > b ? a : b;
}

int main (int argc, char *argv[])
{
    int N;
    read (N);
    register char c;
    long long Answer = 0;
    int now, pos;
    for (register int i, j; N; -- N)
    {
        for (c = getchar (); c == ‘\n‘; c = getchar ());
        
        for (j = now = 1; c != ‘\n‘; c = getchar (), j ++)
        {
            for (pos = 0, i = edge_list[now]; i; i = __next[i])
                if (__key[i] == c)
                {
                    pos = __to[i];
                    break;
                }
            if (!pos)
            {
                pos = ++ Edge_Count;
                __to[Edge_Count] = pos;
                __next[Edge_Count] = edge_list[now];
                edge_list[now] = Edge_Count;
                __key[Edge_Count] = c;
            }
            value[now = pos] ++;
            Answer = max (Answer, (long long) j * value[now]);
        }
    }
    
    printf ("%d", Answer);
    return 0;
} 

#include <cstring>
#include <cstdio>

void read (int &now)
{
    register char word = getchar ();
    for (now = 0; word < ‘0‘ || word > ‘9‘; word = getchar ());
    for (; word >= ‘0‘ && word <= ‘9‘; now = now * 10 + word - ‘0‘, word = getchar ());
}

#define Max 10000060

const int _L = 53;
int Count;

#define INF 1e7

bool visit[Max];

struct T_D 
{    
    T_D *child[_L];
    
    int Flandre;
    int number;
    T_D ()
    {
        for (int i = 0; i < _L; i ++)
            this->child[i] = NULL;
        this->Flandre = 0;
        this->number = ++ Count;
        visit[Count] = true;
    }
};

int value[Max];
int Answer = -INF;

inline int max (int a, int b)
{
    return a > b ? a : b;
}

class Trie_Type
{
    private :
    
        T_D *Root;
        
    public :
        
        Trie_Type ()
        {
            Root = new T_D;
        }
        
        void Insert (char *key)
        {
            T_D *now = Root;
            int Len = strlen (key), Id;
            -- Len;
            for (register int i = 0; i < Len; i ++)
            {
                Id = key[i] - ‘0‘;
                if (!visit[now->number + 1])
                    now->child[Id] = new T_D;
                Answer = max (Answer, now->Flandre * i);
                now = now->child[Id];
            }
        }
        
};

Trie_Type Trie;

char line[Max / 50];
int main (int argc, char *argv[])
{
    int N;
    read (N);
    for (; N; -- N)
    {
        gets (line);
        Trie.Insert (line);
    }
    printf ("%d", Answer);
    
    return 0;
}