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

l = -1
r = t
while r - l > 1:
    c = (l + r) // 2
    print('?', c)
    x, y = map(int, input().split())
    if abs(x-x0) + abs(y-y0) <= abs(x-xt) + abs(y-yt):
        r = c
    else:
        l = c
print('!', r)