def question(K):
    print("?",K,flush=True)
    S=int(input())
    T[K]=S-(K-S)

def answer(L,R):
    print("!",L,R,flush=True)
    exit()

def General_Binary_Increase_Search_Integer(L,R,cond,default=None):
    """条件式が単調増加であるとき, 整数上で二部探索を行う.
    L: 解の下限
    R: 解の上限
    cond: 条件(1変数関数, 広義単調増加を満たす)
    default: Lで条件を満たさないときの返り値
    """
    #if not(cond(R)): return default

    if cond(L): return L

    R+=1
    while R-L>1:
        C=L+(R-L)//2
        if cond(C): R=C
        else: L=C
    return R

def check(x):
    question(x)
    return T[x]*T[N-1]>=0
#==================================================
N=int(input())
T=[None]*(N+1)

question(1); question(N-1)

if T[1]==T[N-1]:
    answer(2,N-1)

M=General_Binary_Increase_Search_Integer(2,N-1,check)

if N//2<=M:
    answer(1,M)
else:
    answer(M+1,N)