def query(x: int) -> bool:
    print(f'? {x}')
    s = input()
    return s == 'safe'


lo = 0
hi = 1000
ans = 0
while lo <= hi:
    m = (lo + hi) // 2
    if query(m):
        ans = max(ans, m)
        lo = m + 1
    else:
        hi = m - 1

print(f'! {ans}')