#include <stdio.h>

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=1; i<n; i++) {
	    int min = 1000000;
	    
	    for (int k=0; k<i; k++) {
		int tmp = 0;
    		for (int j=0; j<7; j++) {
		    if (auta[i][j] != auta[k][j]) {
			tmp++;
		    }
		}
		if (min > tmp) min = tmp;
	    }
	    sum += min;
	}
	printf("The highest possible quality is 1/%ld.\n", sum);
	scanf("%d", &n);
    }
    return 0;
}