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

def kiriage(a, b): return (a+b-1)//b

if X == Y == 0:
    exit(print(0))

if Y >= 0: # 方向転換1回
    ans = (1 if X != 0 else 0) + kiriage(abs(Y), L) + kiriage(abs(X), L)
else: # 方向転換2回
    ans = 2 + kiriage(abs(Y), L) + kiriage(abs(X), L)

print(ans)