#include <string> #include <vector> #include <algorithm> #include <numeric> #include <set> #include <map> #include <queue> #include <iostream> #include <sstream> #include <cstdio> #include <cmath> #include <ctime> #include <cstring> #include <cctype> #include <cassert> #include <limits> #include <functional> #define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i)) #define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i)) #define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i)) #if defined(_MSC_VER) || __cplusplus > 199711L #define aut(r,v) auto r = (v) #else #define aut(r,v) __typeof(v) r = (v) #endif #define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it) #define all(o) (o).begin(), (o).end() #define pb(x) push_back(x) #define mp(x,y) make_pair((x),(y)) #define mset(m,v) memset(m,v,sizeof(m)) #define INF 0x3f3f3f3f #define INFL 0x3f3f3f3f3f3f3f3fLL using namespace std; typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii; typedef long long ll; template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; } template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; } int main() { rep(ii, 1) { const int X = 80; printf("? %d\n", X); fflush(stdout); int c0; scanf("%d", &c0); int ans = -1; if(c0 <= 0) { rep(i, X+1) { printf("? 0\n"); fflush(stdout); int c; scanf("%d", &c); if(c == 0) { ans = i + 1; break; } } }else { int l = X+1, u = (int)1e9; rep(i, 100) { int mid = max(0, (l + u) / 2 - i); printf("? %d\n", mid); fflush(stdout); int c; scanf("%d", &c); if(c == 0) { ans = mid + i; break; } if(c == 1) { l = mid + i + 1; }else { u = mid + i - 1; } } } printf("! %d\n", ans); fflush(stdout); } return 0; }