X,Y,L = input(),input(),input()
count = 0
if (X < 0 or X > 0) and Y < 0:count+=2
elif (X < 0 or X > 0) and Y > 0:count+=1
elif(X == 0) and Y < 0:count += 2
elif Y == 0 and (X < 0 or X > 0):count += 1
X,Y = abs(X),abs(Y) 
count += int(X / L)
if X % L > 0:count += 1
count += int(Y / L)
if Y % L > 0:count += 1
print count