sub a{$c+=print"? @_\n";<>}
$|=1;
if(a(100)<0){
	0while a(0)>0;
}else{
	$l=99;$r=1e9-1;
	$%<0?(--$l,$r=$m-2):($l=$m,--$r)while$%=a($m=$l+$r>>1);
}
print'! ',$m+$c-1,$/