#convert a positive integer to a binary
#string. The input parameter is assumed
#to be a positive integer, the return
#value is the binary string.  This
#illustrates the while statement.

def convert_pos_to_binary(n):
  bin=""
  while n!=0:
    nextbit=n%2
    n=n/2
    bin=str(nextbit)+bin
  return bin

#convert an arbitrary integer to binary
def convert_to_binary(n):
  if n>0:
    return convert_pos_to_binary(n)
  elif n==0:
    return '0'
  elif n<0:
    return "-"+convert_pos_to_binary(-n)