aux x = if rem x 2 == 0 
    then '0' : aux (div x 2) 
    else ('1' : aux (div x 2))
aux x = if rem x 2 == 0 
    then '0' : aux (div x 2) 
    else ('1' : aux (div x 2))
aux x = if rem x 2 == 0 
    then '0' : aux (div x 2) 
    else ('1' : aux (div x 2))