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

if X%L == 0:
    if X < 0:
        X = int(abs(X)/L)+2

    else:
        X = int(abs(X)/L)

elif X%L != 0:
    if X < 0:
        X = int(abs(X)/L)+3

    else:
        X = int(abs(X)/L)+1


if Y%L == 0:
    if Y < 0:
        Y = int(abs(Y)/L)+1

    else:
        Y = int(abs(Y)/L)+1

elif Y%L != 0:
    if Y < 0:
        Y = int(abs(Y)/L)+2

    else:
        Y = int(abs(Y)/L)+2

print(X+Y)