import sys int1 = lambda x: int(x) - 1 # input = lambda: sys.stdin.buffer.readline() input = lambda: sys.stdin.readline().rstrip() ii = lambda: int(input()) i1 = lambda: int1(input()) mi = lambda: map(int, input().split()) mi1 = lambda: map(int1, input().split()) li = lambda: list(mi()) li1 = lambda: list(mi1()) lli = lambda n: [li() for _ in range(n)] INF = float("inf") # mod = int(1e9 + 7) mod = 998244353 n = ii() for x in range(0, n - 1, 2): y = x + 1 print("?", x, y) sys.stdout.flush() z = ii() if z == x: print("!", y) sys.stdout.flush() exit() if z == y: print("!", x) sys.stdout.flush() exit() print("!", n - 1) sys.stdout.flush()