end = 10 ** 3
start = 0
while end - start > 1:
    mid = (start + end) // 2
    print('?',mid)
    ans = input()
    if ans == 'safe':
        start = mid
    else:
        print('?',mid-1)
        ans = input()
        if ans == 'safe':
            start = mid-1
            if end - start == 2:
                end -= 1
            elif end - start == 3:
                print('?',mid + 1)
                ans = input()
                if ans == 'safe':
                    start = ans
                else:
                    end = mid - 1
        else:
            end = mid-1
print('!',start)