def question(t):
    print("?", t)
    return map(int, input().split())

def answer(t):
    print("!", t)

def distance2(x1, y1, x2, y2):
    return (x2-x1)**2 + (y2-y1)**2

T, x0, y0, xt, yt = map(int, input().split())

if (x0, y0) == (xt, yt):
    answer(0)
    exit()

left = 0
right = T
while left+1 < right:
    mid = (left+right)//2
    xn, yn = question(mid)
    if distance2(x0, y0, xn, yn) <= distance2(xn, yn, xt, yt):
        left = mid
    else:
        right = mid

answer(left)