X=int(raw_input())
Y=int(raw_input())
L=int(raw_input())
xlflag = 1
ylflag = 1
xflag = 0
if(X%L==0):
	xlflag = 0
if(Y%L==0):
	ylflag = 0
 
 
if(X!=0):
	if(X>0 or Y==0):
		xflag = 1
	else:
		xflag = 2
 
	print(xflag+int(abs(X)/L)+xlflag+int(abs(Y)/L)+ylflag)
else:
	if(Y>=0):
		print (int(abs(Y)/L)+ylflag)
	else:
		print (2+int(abs(Y)/L)+ylflag)