def is_safe(n):
    print(f'? {n}', flush=True)
    return input() == 'safe'


def main():
    out = 10**3
    safe = 0
    while safe + 1 < out:
        q = (safe + out)//2
        if is_safe(q):
            safe = q
        elif q+1 < out and is_safe(q+1):
            safe = q+1
        else:
            out = q
    print(f'! {safe}', flush=True)


if __name__ == "__main__":
    main()