#include <bits/stdc++.h>
using namespace std;
struct Mod {
  const long long M;
  Mod(long long M) : M(M) {}
  long long ok(long long a) const {
    for (a %= M; a < 0;) a += M;
    return a;
  }
  long long add(long long a, long long b) const { return ok(a + b); }
  long long mul(long long a, long long b) const { return ok(a * b); }
  long long pow(long long a, long long b) const {
    long long r = 1;
    for (a = ok(a); b; b >>= 1, a = mul(a, a))
      if (b & 1) r = mul(r, a);
    return r;
  }
  long long inv(long long a) const { return pow(a, M - 2); }
} M(1e6 + 3);
int main() {
  vector<pair<long long, long long>> p;
  for (long long i = 0, j; i < 11; ++i) {
    printf("? %lld\n", i), fflush(stdout);
    scanf("%lld", &j);
    p.push_back({i, j % M.M});
  }
  vector<long long> lagrange(p.size()), sum(p.size());
  lagrange[0] = p[0].second;
  for (int i = sum[0] = 1; i < p.size(); ++i) {
    for (int j = p.size() - 1; j >= i; --j)
      p[j].second = M.mul(p[j].second - p[j - 1].second,
                          M.inv(p[j].first - p[j - i].first));
    for (int j = i; ~j; --j) {
      sum[j] = M.add(j ? sum[j - 1] : 0, -M.mul(sum[j], p[i - 1].first));
      lagrange[j] = M.add(lagrange[j], M.mul(sum[j], p[i].second));
    }
  }
  for (long long i = 0, sum; i < M.M; ++i) {
    for (long long j = sum = 0, x = 1; j < lagrange.size();
         ++j, x = M.mul(x, i))
      sum = M.add(sum, M.mul(x, lagrange[j]));
    if (!sum) return printf("! %d", i), 0;
  }
  printf("! -1");
}
