X = int(input())
Y = int(input())
L = int(input())
def need(a,b):
    if a%b == 0:
        return abs(a)/b
    else:
        return abs(a)//b+1
c = need(X,L)+need(Y,L)
sum = 0
if X != 0 and Y != 0:
    sum += 1
else:
    sum += 0
ans = c+sum
print(ans)