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