X, Y, L = int(input()), int(input()), int(input())
ans = 0
if X == Y == 0:
    print(0)
    exit()

if X == 0 and Y > 0:
    ans += 0
elif Y >= 0:
    ans += 1
else:
    ans += 2

X_count, Y_count = 0, 0

if abs(X) % L == 0:
    X_count = abs(X) // L
else:
    X_count = abs(X) // L + 1


if abs(Y) % L == 0:
    Y_count = abs(Y) // L
else:
    Y_count = abs(Y) // L + 1

print(ans+X_count+Y_count)