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

cnt=0
if (Y>0 and X<0) or (Y>0 and X>0):
    cnt=1
    if Y%L==0:
        cnt+=Y//L
    else:
        cnt+=Y//L+1
    if abs(X)%L==0:
        cnt+=abs(X)//L
    else:
        cnt+=abs(X)//L+1
elif Y>0 and X==0:
    if Y%L==0:
        cnt+=Y//L
    else:
        cnt+=Y//L+1
if (Y<0 and X<0) or (Y<0 and X>0):
    cnt=2
    if abs(Y)%L==0:
        cnt+=abs(Y)//L
    else:
        cnt+=abs(Y)//L+1
    if abs(X)%L==0:
        cnt+=abs(X)//L
    else:
        cnt+=abs(X)//L+1
elif Y<0 and X==0:
    cnt+=2
    if abs(Y)%L==0:
        cnt+=abs(Y)//L
    else:
        cnt+=abs(Y)//L+1

print(cnt)