#include <stdio.h>


char data[10000][10];
int sums[10000];
char line[100];
int n;

int main() {
	int i,j,k,s;
	int m;
	while(1) {
		gets(line);
		sscanf(line,"%d",&n);
		if (!n)
			break;

		i = n;
		while (i--) {
			gets(data[i]);
			sums[i] = 0;
		}

		for(i = 0; i < n; i++) {
			for (j = i+1; j < n; j++) {
				s = 0;
				for (k = 0; k < 7; k++) {
					if (data[i][k] != data[j][k]) 
						s++;
				}
				sums[i] += s;
				sums[j] += s;
			}
		}

		m = sums[0];
		for (i = 1; i < n; i++) {
			if (m > sums[i])
				m = sums[i];
		}

		printf("The highest possible quality is 1/%d.\n",m);
	}
	return 0;
}