import math

x = abs(int(input()))
y = abs(int(input()))
l = int(input())

execution_count = 0

if x != 0:
    execution_count += math.ceil(x / l)
if x != 0 and y != 0:
    execution_count += 1
if y != 0:
    execution_count += math.ceil(y / l)

print(execution_count)