import sys
f=sys.stdout.flush
l=0;r=10**9+1
count = 0
while-~l<r:
 m=(l+r)/2
 print"?",m;f()
 if-~input():l=m
 else:r=m
 count += 1
 if count==100:break
 l=max(l-1,0);r=max(r-1,1)
print"!",l;f()