import sys
input = sys.stdin.readline

N=int(input())

print("?",1,flush=True)
x=int(input())
init=x
print("?",N-1,flush=True)
y=int(input())

if x==1 and y==N//2:
    print("!",2,N-1,flush=True)
    exit()
elif x==0 and y==N//2-1:
    print("!",2,N-1,flush=True)
    exit()

# 1～xの表 - 裏の枚数が0になるものを探す

MIN=2
MAX=N-1

while True:
    mid=(MIN+MAX)//2

    print("?",mid,flush=True)
    x=int(input())
    y=mid-x

    if init==1:
        if x<y:
            MAX=mid
        elif x>y:
            MIN=mid
        else:
            break
    else:
        if x>y:
            MAX=mid
        elif x<y:
            MIN=mid
        else:
            break
        

if mid>=N//2:
    print("!",1,mid,flush=True)
else:
    print("!",mid+1,N,flush=True)