#include <stdio.h>
int max = 1000;
int used[2055];
int who[20033];
int kolik[10];


int last[10];
int main() {
    int n;
    char auta[2005][10];
    scanf("%d", &n);
    while (n != 0) {
	long sum = 0;
	for (int i=0; i<n; i++) {
	    scanf("%s", auta[i]);
	    for (int i=0; i<n; i++) {
		used[i] = 0;
		who[i] = 0;
	    }
	}
	used[0] = 1;
	for (int i=0; i<n; i++) {
	    int min = max;
	    int yes = 0;
	    for (int z=0; z<7; z++) { kolik[z] = 0; last[z] = 0;}
	    for (int k=i+1; k<n; k++) {
		if (k <= i) break;
		int tmp = 0;
    		for (int j=0; j<7; j++) {
		    if (auta[i][j] != auta[k][j]) {
			yes = 1;
			tmp++;
		    }
		}
		last[tmp] = k;
		kolik[tmp]++;
		yes = 0;
	    }
		for (int t=0; t<7; t++) {
		    if (kolik[t] == 1) {
			sum+=t;
			break;
		    }
		}
		
	}
	printf("The highest possible quality is 1/%ld.\n", sum);
	scanf("%d", &n);
    }
    return 0;
}