x, y, r = map(int, input().split())

for c in range(abs(x) + abs(y), 401):
    flag = True
    for xx in range(-c, c + 1):
        yy = c - abs(xx)
        if (xx - x)**2 + (yy - y)**2 <= r**2:
            flag = False
            break
        yy *= -1
        if (xx - x)**2 + (yy - y)**2 <= r**2:
            flag = False
            break
    if flag:
        print(c)
        break