MIN = 1
MAX = 10 ** 6
print('?', MIN)
X = [MIN]
l = MIN
r = MAX
while r - l > 1:
    x = l + r - X[-1]
    print('?', x)
    c = int(input())
    if c == 1:
        if x < X[-1]:
            r = (x + X[-1]) // 2
        else:
            l = (x + X[-1]) // 2
    else:
        if x < X[-1]:
            l = (x + X[-1]) // 2
        else:
            r = (x + X[-1]) // 2
    X.append(x)
print('?', l)
c = int(input())
print('?', r)
c = int(input())
if c == 1:
    print('!', r)
else:
    print('!', l)