#include <bits/stdc++.h>
using namespace std;
template <typename T>
void out(T x) {
  cout << x << endl;
  exit(0);
}
const long long mod = 1e9 + 7;
const int maxn = 1e6 + 5;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int n, start, x;
int ans = 1e9 + 10;
int beforeVal = -1;
int beforeIdx;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> start >> x;
  beforeIdx = start;
  vector<int> v;
  for (int i = 1; i <= n; i++) {
    v.push_back(i);
  }
  shuffle(v.begin(), v.end(), rng);
  v.resize(min(n, 999));
  for (int q : v) {
    cout << "? " << q << endl;
    cout.flush();
    int val;
    int nxt;
    cin >> val >> nxt;
    if (val >= x) {
      ans = min(ans, val);
    } else {
      if (val > beforeVal) {
        beforeVal = val;
        beforeIdx = nxt;
      }
    }
  }
  for (int i = 0; i < 1000; i++) {
    if (beforeIdx == -1) break;
    cout << "? " << beforeIdx << endl;
    cout.flush();
    int val;
    int nxt;
    cin >> val >> nxt;
    if (val >= x) {
      ans = min(ans, val);
    }
    beforeIdx = nxt;
  }
  if (ans == 1e9 + 10) ans = -1;
  cout << "! " << ans << endl;
  cout.flush();
  return 0;
}
