import sys
X=int(input())
Y=int(input())
L=int(input())

i=0

if X==0 and Y==0:
 print(int(i)) 
 sys.exit()

if Y>0:
 if Y%L == 0:
  i+=Y/L

 else:
  i+=Y//L+1

 if X!=0:
  i+=1
  X2=abs(X)

  if X2%L == 0:
   i+=X2/L

  else:
   i+=X2//L+1 

else:
 i+=1
 if X!=0:
  X2=abs(X)

  if X2%L == 0:
   i+=X2/L

  else:
   i+=X2//L+1
 
  if Y==0:
   print(int(i)) 
   sys.exit()

 i+=1
 
 Y2=abs(Y)
 if Y2%L == 0:
  i+=Y2/L

 else:
  i+=Y2//L+1

print(int(i))