#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>

#define DBG 0

int get_line(char *s, int max)
{
    int i;
    fgets(s,max,stdin);
    i = strlen(s) - 1;
    while (i >= 0 && s[i] == '\n')
        i--;
    i++;
    s[i] = 0;
    return i;
}

int sgetint(char **s, int *x)
{
    char *t = *s;
    
    while (isspace(*t)) t++;
    if (sscanf(t,"%d",x) != 1) return 0;
    while (*t && !isspace(*t)) t++;
    *s = t;
    return 1;
}
int dist(char * s, char * q)
{
	int di = 0;
	if (s == q)
		return 0;
	while (*s)
		di += *s++ != *q++;
	return di;
}

char kody[2002][12];
int graf[2002][2002];

int main(void)
{
	char line[50], *s = line;
	int N,i,j,min,run;
	while (1) {
		scanf("%d\n",&N);
		if (!N)
			break;
		for (i = 0 ; i < N ; i++) {
			get_line(kody[i],9);
		}
		for (i = 0 ; i < N ; i++)
			for (j = 0 ; j < i ; j++ ) {
				graf[j][i] = graf[i][j] = dist(kody[i],kody[j]);
			}
		;
		min = 0x7fffffff;
		for (i = 0 ; i < N ; i++) {
			run = 0;
			for (j = 0 ; j < N ; j++ ) {
				run += graf[i][j];
			}
			if (min > run)
				min = run;
		}
		printf("The highest possible quality is 1/%d.\n",min);
	}
	return 0;
}