Program history;
Var 
  N,i : integer;
  
  S: array[1..2000] of string(7);

function compare(s1,s2: string):integer;
var counter:integer;
begin
 counter:=0;
  for i:=1 to 7 do
   if (s1[i]<> s2[i]) then inc(counter);
   
   compare:= counter;
end;

procedure doIt;
var 
 counter,i,j,min:integer;
 orig : string(7);
begin
   for i:=1 to N do
     begin
        counter :=0;
        orig:=s[i];
	for j:=1 to N do 
	  begin
	     counter:=counter + compare(orig,s[j]);
	  end;
	  if (i=1) then min := counter;
	  if (counter < min) then min := counter;
     end; 	
     writeln('The highest possible quality is 1/',min,'.');
end;

Begin
 Repeat
   Readln(N);
   if N>=2 then
     begin
       for i:=1 to N do
         begin
	   readln(S[i]);
	 end; 
	 doIt;
     end;
 Until N=0;
End.