#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
template <typename T>
T gcd(T a, T b) {
  return b == 0 ? a : gcd(b, a % b);
}
template <typename T>
T LCM(T a, T b) {
  return a * (b / gcd(a, b));
}
template <typename T>
T expo(T base, T e, T mod) {
  T res = 1;
  while (e > 0) {
    if (e & 1) res = res * base % mod;
    base = base * base % mod;
    e >>= 1;
  }
  return res;
}
template <typename T, typename second>
T expo(T b, second e) {
  if (e <= 1) return e == 0 ? 1 : b;
  return (e & 1) == 0 ? expo((b * b), e >> 1) : (b * expo((b * b), e >> 1));
}
template <typename T, typename second>
T modinv(T a, second mod) {
  return expo(a, mod - 2, mod);
}
template <class T, class second>
std::ostream &operator<<(std::ostream &os, const std::pair<T, second> &t) {
  os << "(" << t.first << ", " << t.second << ")";
  return os;
}
template <class T>
std::ostream &operator<<(std::ostream &os, const std::vector<T> &t) {
  os << "[";
  for (__typeof(t.begin()) it = t.begin(); it != t.end(); it++) {
    if (it != t.begin()) os << ", ";
    os << *it;
  }
  os << "]";
  return os;
}
template <typename T>
void in(T &x) {
  T c = getchar();
  while (((c < 48) || (c > 57)) && (c != '-')) c = getchar();
  bool neg = false;
  if (c == '-') neg = true;
  x = 0;
  for (; c < 48 || c > 57; c = getchar())
    ;
  for (; c > 47 && c < 58; c = getchar()) x = (x * 10) + (c - 48);
  if (neg) x = -x;
}
const int MAXN = 5e4 + 100;
const int FF = 1500;
int n, start, x;
int times;
pair<int, int> Ask(int idx) {
  times++;
  assert(times < 2000);
  printf("? %d\n", idx);
  fflush(stdout);
  pair<int, int> res;
  scanf("%d %d", &res.first, &res.second);
  return res;
}
void Give(int val) {
  printf("! %d\n", val);
  fflush(stdout);
}
vector<int> perm;
int main() {
  srand(time(NULL));
  in(n), in(start), in(x);
  for (int i = 1; i <= n; i++) {
    perm.push_back(i);
  }
  random_shuffle(perm.begin(), perm.end());
  for (int i = 0; i < perm.size(); i++) {
    if (perm[i] == start) {
      swap(perm[i], perm[0]);
    }
  }
  pair<int, int> qs = {-1, -1}, ff;
  bool ok = false;
  int iter;
  int up = min((int)perm.size(), FF);
  for (iter = 0; iter < up; iter++) {
    ff = Ask(perm[iter]);
    if (ff.second == -1 && ff.first < x) {
      Give(-1);
      return 0;
    } else if (ff.first == x) {
      Give(ff.first);
      return 0;
    } else if (ff.first < x && ff.first > qs.first) {
      ok = true;
      qs = ff;
    }
  }
  if (!ok) {
    qs.second = start;
  }
  while (times < 1999) {
    qs = Ask(qs.second);
    if (qs.second == -1 && qs.first < x) {
      Give(-1);
      return 0;
    } else if (qs.first >= x) {
      Give(qs.first);
      return 0;
    }
  }
  Give(-1);
  return 0;
}
