#include <bits/stdc++.h>
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx")
using namespace std;
inline bool isDigit(char c) { return '0' <= c && c <= '9'; }
template <class T>
inline T sqr(T x) {
  return x * x;
}
template <class T>
inline bool isSquare(T x) {
  int y = sqrt(x + 0.5);
  return (y * y) == x;
}
template <class T1, class T2>
inline T1 gcd(T1 a, T2 b) {
  return b ? gcd(b, a % b) : a;
}
template <class T1, class T2>
inline T1 eqMin(T1& x, const T2& y) {
  if (T1(y) < x) return x = y;
  return x;
}
template <class T1, class T2>
inline T1 eqMax(T1& x, const T2& y) {
  if (T1(y) > x) return x = y;
  return x;
}
template <class T1, class T2>
inline T1 min(const T1& x, const T2& y) {
  return x < (T1)y ? x : (T1)y;
}
template <class T1, class T2>
inline T1 max(T1& x, const T2& y) {
  return x > (T1)y ? x : (T1)y;
}
template <typename T>
inline T getint() {
  T x = 0, p = 1;
  char ch;
  do {
    ch = getchar();
  } while (ch <= ' ');
  if (ch == '-') p = -1, ch = getchar();
  while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar();
  return x * p;
}
template <class T1, class T2>
ostream& operator<<(ostream& os, const pair<T1, T2>& p) {
  return os << '(' << p.first << ", " << p.second << ')';
}
template <class T>
ostream& operator<<(ostream& os, const vector<T>& v) {
  os << '{';
  bool was = false;
  for (const T& x : v) {
    if (was) os << ", ";
    was = true;
    os << x;
  }
  os << '}';
  return os;
}
template <class T>
ostream& operator<<(ostream& os, const set<T>& v) {
  os << '[';
  bool was = false;
  for (const T& x : v) {
    if (was) os << ", ";
    was = true;
    os << x;
  }
  os << ']';
  return os;
}
template <class T>
ostream& operator<<(ostream& os, const multiset<T>& v) {
  os << '[';
  bool was = false;
  for (const T& x : v) {
    if (was) os << ", ";
    was = true;
    os << x;
  }
  os << ']';
  return os;
}
template <class T1, class T2>
ostream& operator<<(ostream& os, const map<T1, T2>& m) {
  os << '<';
  bool was = false;
  for (const auto& x : m) {
    if (was) os << ", ";
    was = true;
    os << x;
  }
  os << '>';
  return os;
}
template <size_t sz>
ostream& operator<<(ostream& os, const bitset<sz>& bit) {
  os << '/';
  for (int i = 0; i < sz; i++) os << bit[i];
  os << '\\';
  return os;
}
const double PI = acos(-1);
const double EPS = 1e-8;
const int INF = (int)2e9;
const long long LINF = (long long)2e18;
const int MOD = (int)1e9 + 7;
const int MAXN = (int)1e5 + 10;
int n, s, x;
int val[MAXN], nxt[MAXN];
int p[MAXN];
bool us[MAXN];
int cnt = 0;
void read(int x) {
  if (us[x]) return;
  us[x] = true;
  cout << "? " << x << "\n";
  cout.flush();
  cin >> val[x] >> nxt[x];
  cout.flush();
}
int main() {
  ios_base::sync_with_stdio(false);
  srand(time(NULL));
  cin >> n >> s >> x;
  cout.flush();
  for (int i = 1; i <= n; i++) {
    p[i] = i;
  }
  random_shuffle(p + 1, p + n + 1);
  read(s);
  int ss = s;
  s = 0;
  val[0] = -1;
  for (int i = 1; i <= min(n / 2, 1300); i++) {
    read(p[i]);
    if (val[p[i]] < x && val[p[i]] > val[s]) {
      s = p[i];
    }
  }
  if (val[ss] < x && val[ss] > val[s]) {
    s = ss;
  }
  if (s) {
    while (val[s] < x) {
      s = nxt[s];
      if (s == -1) {
        cout << "! -1"
             << "\n";
        cout.flush();
        return 0;
      }
      read(s);
      if (val[s] >= x) {
        cout << "! " << val[s] << "\n";
        cout.flush();
        return 0;
      }
      if (nxt[s] == -1) {
        cout << "! -1"
             << "\n";
        cout.flush();
        return 0;
      }
    }
  }
  cout << "! " << val[ss] << "\n";
  cout.flush();
}
