import math

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

if X == 0:
    Nx = 0
else:
    Nx = (abs(X) + L - 1) // L

if Y == 0:
    Ny = 0
else:
    Ny = (abs(Y) + L - 1) // L
    

total_forward_moves = Nx + Ny

if X == 0 and Y == 0:
    print(0)
    
elif X == 0:
    if Y > 0:
        print(total_forward_moves)
    else:
        print(total_forward_moves + 2)

elif Y == 0:
    print(total_forward_moves + 1)

else:
    if Y > 0:
       
        print(total_forward_moves + 1)
    else: 
        print(total_forward_moves + 2)