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


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;
	    }
	}
	used[0] = 1;
	for (int i=1; i<n; i++) {
	    int min = max;
	    int yes = 0;
	    for (int k=0; k<i; k++) {
//		if (i >= k) continue;
		int tmp = 0;
    		for (int j=0; j<7; j++) {
		    if (auta[i][j] != auta[k][j]) {
			yes = 1;
			tmp++;
		    }
		}
		if (min > tmp && yes == 1) {
		    min = tmp;
		}
		yes = 0;
	    }
	    if (min != max) {
    		sum += min;
	    }
	}
	printf("The highest possible quality is 1/%ld.\n", sum);
	scanf("%d", &n);
    }
    return 0;
}