X = int(input())
Y = int(input())
L = int(input())
goal = [X, Y] 
koudou = 0
if(Y > 0):#北
    while(True):
        if(Y <= 0):
            break
        Y -= L
        koudou += 1
                
elif(Y < 0):#南
        koudou += 1
        while(True):
            if(Y >= 0):
                break
            Y += L
            koudou += 1
                
if(X > 0):#東
        koudou += 1
        while(True):
            if(X <= 0):
                break
            X -= L
            koudou += 1
                
elif(X < 0):#西
        koudou += 1
        while(True):
            if(X >= 0):
                break
            X += L
            koudou += 1
print(koudou)