m = map(int, raw_input().split())
c = 0

if m[0] < m[1]:
 for i in xrange(m[0],m[1]):
  if i % m[2] == 0:
   c = c + 1
 print c




else:
 for i in xrange(m[0],m[1]):
  if i % m[2] == 0:
   c = c + 1
 print c