from math import ceil
def MIN(X, Y, L):
    distance = abs(X) + abs(Y)
    if distance == 0:
        return 0
    elif distance <= L:
        return 2
    else:
        return ceil(distance / L) + (distance % L != 0)
X = int(input())
Y = int(input())
L = int(input())
print(MIN(X, Y, L))