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

if X != 0:
    A = (abs(X)+ L-1)//L
else:
    A = 0

if Y != 0:
    B = (abs(Y)+L-1)//L
else:
    B = 0

if Y <0:
    C = 2
elif X == 0 and Y >0:
    C = 0
elif X != 0 and Y >=0:
    C = 1
print(A+B+C)