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
            end = mid
        else:
            end = mid-1
print('!',start)