import numpy as np
X=int(input())
Y=int(input())
L=int(input())
order=0
if X==0 and Y==0:
    pass
elif Y<0:
    order+=2
elif X==0:
    pass
else:
    order+=1
order+=int(np.ceil(abs(X)/L)+np.ceil(abs(Y)/L))
print(order)