import math



X = int(input())

Y = int(input())

L = int(input())

ans = math.ceil(abs(X) / L) + math.ceil(abs(Y) / L)

if Y < 0:
    
    print(ans + 2)
    
else:
    if X == 0:
        
        print(ans)
        
    else:
        
        print(ans + 1)