T,a,b,c,d=map(int,input().split())
l=0
r=T
if (a+b-(c+d))%2==1:
  print('!','NaN')
  exit()
while True:
  m=(l+r)//2
  print('?',m,flush=True)
  x,y=map(int,input().split())
  s0=abs(x-a)+abs(y-b)
  s1=abs(x-c)+abs(y-d)
  if s0==s1:
    print('!',m,flush=True)
    exit()
  if s0<s1:
    l=m+1
  else:
    r=m-1