X=int(input())
Y=int(input())
L=int(input())
if X % L == 0 and abs(X) >= L:
    x = X // L
elif X % L != 0 and abs(X) >= L:
    x = X // L + 1
else:
    x = 1
if Y % L == 0 and abs(Y) >= L:
    y = Y // L
if Y % L != 0 and abs(Y) >= L:
    y = Y // L + 1
else:
    y = 1
x = abs(x)
y = abs(y)
if X == 0 and Y > 0:
    print(x+y)
elif Y > 0:
    print(x+y+1)
elif Y < 0:
    print(x+y+2)