/* ***********************************************

 Author        :Sun Yuefeng

 Created Time  :2016/10/16 20:17:34

 File Name     :A.cpp

 ************************************************ */

 #include <stdio.h>

 #include <string.h>

 #include <iostream>

 #include <algorithm>

 #include <vector>

 #include <queue>

 #include <set>

 #include <map>

 #include <string>

 #include <math.h>

 #include <stdlib.h>

 #include <time.h>

 #define M(a,b) memset(a,b,sizeof(a))

 using namespace std;

 const int maxn=;

 const int inf=0x3f3f3f3f;

 int n,sum,ans;

 char dance[][maxn];

 int match[maxn][maxn];

 int way[];

 bool vis[maxn];

 int solve(int x,int y){ //看两个舞蹈有几个人重复了

     int sum=;

     int lenx=strlen(dance[x]);

     int leny=strlen(dance[y]);

     for(int i=;i<lenx;i++)

         for(int j=;j<leny;j++)

             sum+=(dance[x][i]==dance[y][j]);

     return sum;

 }

 void dfs(int x){ //强行遍历

     if(x>n){

         if(sum<ans) ans=sum;

         return ;

     }

     for(int i=;i<=n;i++){ //遍历部分

         if(!vis[i]){

             way[x]=i;

             vis[i]=true;

             sum+=match[way[x-]][i];

             dfs(x+);

             sum-=match[way[x-]][i];

             vis[i]=false;

         }

     }

 }

 int main()

 {

     //freopen("in.txt","r",stdin);

     //freopen("out.txt","w",stdout);

     while(~scanf("%d",&n)){

         getchar();

         M(vis,false),M(match,),M(way,);

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

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

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

             for(int j=;j<=n;j++){

                 if(i!=j)

                     match[i][j]=match[j][i]=solve(i,j); //预处理匹配状况

             }

         }

         ans=inf; //初始化ans sum

         sum=;

         dfs(); //搜索

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

     }

     return ;

 }

 /*

 5

 ABC

 ABEF

 DEF

 ABCDE

 FGH

 6

 BDE

 FGH

 DEF

 ABC

 BDE

 ABEF

 4

 XYZ

 XYZ

 ABYZ

 Z

 */