import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter; import java.util.NoSuchElementException; public class Main { static FastScanner scan = new FastScanner(); static PrintWriter out = new PrintWriter(System.out); public static void main(String[] args) { int res = ask(100); if(res == 0) { System.out.println("! 100"); return; } else if(res < 0) { for(int i=2; i<=100; i++) { res = ask(0); if(res == 0) { System.out.println("! " + (i-1)); return; } } } int l = 100; int r = 1000000000; int m = 0; int count = 1; while(l < r) { m = (l+r)/2; res = ask(m-count); count++; if(res == 0) { System.out.println("! " + m); return; } else if(res > 0) { l = m+1; } else { r = m; } } System.out.println("! " + l); } static int ask(int y) { out.println("? " + y); out.flush(); int res = scan.nextInt(); return res; } static class FastScanner { private final InputStream in = System.in; private final byte[] buffer = new byte[1024]; private int ptr = 0; private int buflen = 0; private boolean hasNextByte() { if (ptr < buflen) { return true; } else { ptr = 0; try { buflen = in.read(buffer); } catch (IOException e) { e.printStackTrace(); } if (buflen <= 0) { return false; } } return true; } private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1; } private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126; } private void skipUnprintable() { while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; } public boolean hasNext() { skipUnprintable(); return hasNextByte(); } public String next() { if (!hasNext()) throw new NoSuchElementException(); StringBuilder sb = new StringBuilder(); int b = readByte(); while (isPrintableChar(b)) { sb.appendCodePoint(b); b = readByte(); } return sb.toString(); } public int nextInt() { return (int) nextLong(); } public long nextLong() { if (!hasNext()) throw new NoSuchElementException(); long n = 0; boolean minus = false; int b = readByte(); if (b == '-') { minus = true; b = readByte(); } if (b < '0' || '9' < b) { throw new NumberFormatException(); } while (true) { if ('0' <= b && b <= '9') { n *= 10; n += b - '0'; } else if (b == -1 || !isPrintableChar(b)) { return minus ? -n : n; } else { throw new NumberFormatException(); } b = readByte(); } } } }