X = int(input())
Y = int(input())
L = int(input())
rota = 0
gost = 0
if Y > 0:
    if X != 0:
        rota += 1
elif Y == 0:
    if X != 0:
        rota += 1
else:
    if X == 0:
        rota += 2
    else:
        rota += 2
#print(rota)        
if X % L == 0:
    gost += abs(X // L)
elif X < 0:
    gost += abs(X // L) 
else:
    gost += abs(x//L)+1
if Y % L == 0:
    gost += abs(Y //L)
elif Y < 0 :
    gost += abs(Y//L) 
else:
    gost += abs(Y//L) +1
#print(gost)   
print(rota+gost)