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()

#==================================================
N=int(input())
T=[None]*(N+1)

question(1); question(N-1)

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

L,R=1,N-1
while True:
    C=(L+R)//2
    question(C)
    if T[C]==0:
        break
    elif T[C]*T[N-1]>0:
        R=C
    else:
        L=C+1

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