package contest; import java.io.PrintWriter; import java.util.Arrays; import java.util.Scanner; public class Q687 { static Scanner in; static PrintWriter out; static String INPUT = ""; static void solve() { long low = 10, high = 1000000001; for(long i = low;;i*=2){ out.println("? " + i); out.flush(); int res = ni(); if(res == 0){ low = i; high = i; out.println("! " + (low-1)); out.flush(); return; }else if(res == 1){ low = i+1; }else{ high = i; break; } low--; high--; } low--; high--; while(true){ long h = high+low>>>1; out.println("? " + h); out.flush(); int res = ni(); if(res == 0){ low = h; high = h; out.println("! " + (low-1)); out.flush(); return; }else if(res == 1){ low = h+1; }else{ high = h; } low--; high--; } } public static void main(String[] args) throws Exception { in = INPUT.isEmpty() ? new Scanner(System.in) : new Scanner(INPUT); out = new PrintWriter(System.out); solve(); out.flush(); } static int ni() { return Integer.parseInt(in.next()); } static long nl() { return Long.parseLong(in.next()); } static double nd() { return Double.parseDouble(in.next()); } static void tr(Object... o) { if(INPUT.length() != 0)System.out.println(Arrays.deepToString(o)); } }