ok, ng = 0, 10**3 + 1
while ng - ok > 1:
    mid = (ok + ng) // 2
    print(f"? {mid}")
    s = input()
    if s == "safe":
        ok = mid
    elif s == "out":
        print(f"? {mid + 1}")
        s = input()
        if s == "safe":
            ok = mid + 1
        elif s == "out":
            ng = mid
print(f"! {ok}")