Program MaxComDiv1;
 var a,b,r:longint;
Begin writeln('Massimo comun divisore di a e b.');
 repeat write('a (0 per fine) =');readln(a);
  if a=0 then Halt;
  write('b (0 per fine) =');readln(b);
  if b=0 then Halt;
  while b>0 do                   (*algoritmo euclideo*)
  begin r:=a mod b;a:=b;b:=r     (*delle divisioni successive*)
  end;
  writeln('  M.C.D.=',a)
 until false
END.