#include <bits/stdc++.h>
using namespace std;
const int N = 110, mod = 1e6 + 3;
long long v[N], w[N], c[N], g[N][N], xs[N];
void Mul(long long &x, long long y) { x = (x * y) % mod; }
void Add(long long &x, long long y) { x = (x + y + mod) % mod; }
long long add(long long x, long long y) { return (x + y + mod) % mod; }
long long mul(long long x, long long y) { return x * y % mod; }
long long q_pow(long long x, int y) {
  long long ans = 1;
  for (; y; y >>= 1) {
    if (y & 1) Mul(ans, x);
    Mul(x, x);
  }
  return ans;
}
void Get(int k) {
  for (int i = 1; i <= k + 1; ++i) {
    long long pos = 1;
    for (int j = 0; j <= k; ++j) {
      g[i][j] = pos;
      Mul(pos, i);
    }
    g[i][k + 1] = v[i];
  }
  for (int i = 1; i <= k + 1; ++i) {
    for (int j = 1; j <= k + 1; ++j) {
      if (j == i) continue;
      long long gg = mul(g[j][i - 1], q_pow(g[i][i - 1], mod - 2));
      for (int t = 0; t <= k + 1; ++t) Add(g[j][t], -mul(gg, g[i][t]));
    }
  }
  for (int i = 1; i <= k + 1; ++i)
    xs[i - 1] = mul(g[i][k + 1], q_pow(g[i][i - 1], mod - 2));
}
long long js(int x, int k) {
  long long pos = 1, ans = 0;
  for (int i = 0; i <= k; ++i) Add(ans, mul(pos, xs[i])), Mul(pos, x);
  return ans;
}
int main() {
  for (int i = 1; i <= 20; ++i) {
    printf("? %d\n", i);
    fflush(stdout);
    scanf("%lld", &v[i]);
    w[i] = v[i];
  }
  int k = 0;
  for (;;) {
    int res = 0;
    for (int i = 1; i <= 19 - k; ++i) w[i] = add(w[i + 1], -w[i]);
    for (int i = 1; i <= 19 - k; ++i)
      if (!w[i]) res++;
    if (res == 19 - k) break;
    k++;
  }
  Get(k);
  for (int i = 0; i <= mod - 1; ++i)
    if (!js(i, k)) return printf("! %d\n", i), 0;
  printf("! -1\n");
  return 0;
}
