#include<iostream>
#include<string>
#include<cstring>
using namespace std;
const int maxn=2005;
const int inf=0x3f3f3f3f; 
double m[maxn][maxn],low[maxn];
bool vis[maxn];
string str[maxn];
int n;

int dist(string s1,string s2)
{
	int cnt=0;
	for(int i=0;i<7;i++)
		if(s1[i]!=s2[i])
			cnt++;
	return cnt;
}

int prim()
{
	memset(vis,false,sizeof(vis));
	memset(low,0,sizeof(low));
	for(int i=1;i<=n;i++)
		low[i]=m[1][i];
	vis[1]=1;
	int sum=0;
	int t;
	for(int i=1;i<n;i++)//执行n-1次 
	{
		int min=inf;
		for(int j=1;j<=n;j++)//找最小 
		{
			if(!vis[j]&&low[j]<min)
			{
				min=low[j];
				t=j;
			}
		}
		sum+=min;
		vis[t]=1;
		for(int j=1;j<=n;j++)//更新
		{
			if(!vis[j]&&low[j]>m[t][j])
				low[j]=m[t][j];
		}	 
	}
	return sum;
}

int main()
{
	while(cin>>n&&n)
	{
		for(int i=1;i<=n;i++)
			cin>>str[i];
		for(int i=1;i<=n;i++)
			for(int j=i+1;j<=n;j++)
				m[i][j]=m[j][i]=dist(str[i],str[j]);
		int ans=prim();
		if(ans==1)
			cout<<"The highest possible quality is 1."<<endl;
		else
			cout<<"The highest possible quality is 1/"<<ans<<"."<<endl;
	}
	return 0;
}