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


cnt = 0

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