#include <stdio.h>

int main(void)
{
    char line[2001][8];        
    int i,j,delka, rozdil, celkovy;
    
    scanf("%d\n",&delka);

while(delka != 0) {
        
    for(i=0;i<delka;i++)
    {
        line[i][0] = '\0';
    	gets(line[i]);
    }
    
    for(i=0;i<delka;i++){
	rozdil = 0;
	for(j=0;j<delka;j++) {
	    if(i!=j){
    		if(line[i][0]!= line[j][0]) rozdil++;
    	        if(line[i][1]!= line[j][1]) rozdil++;
		if(line[i][2]!= line[j][2]) rozdil++;
		if(line[i][3]!= line[j][3]) rozdil++;
		if(line[i][4]!= line[j][4]) rozdil++;
	        if(line[i][5]!= line[j][5]) rozdil++;
		if(line[i][6]!= line[j][6]) rozdil++;
	    }
	}
	if(i==0) celkovy = rozdil;
	else
	    if(celkovy>rozdil) celkovy = rozdil;
    }
    printf("The highest possible quality is 1/%d.\n",celkovy);
    
    scanf("%d\n", &delka);

}

    return 0;
}