ok = 0
ng = 1000
while ng - ok > 1:
    mid = (ok + ng) // 2
    print('?', mid)
    u = input()
    print('?', mid+1)
    v = input()
    if v == "safe":
        ok = mid + 1
    elif u == "safe":
        ok = mid
    else:
        ng = mid
print('!', ok)