#include <bits/stdc++.h>
using namespace std;
template <typename T, typename U>
inline void smin(T &a, const U &b) {
  if (a > b) a = b;
}
template <typename T, typename U>
inline void smax(T &a, const U &b) {
  if (a < b) a = b;
}
template <typename T>
inline void gn(T &first) {
  char c, sg = 0;
  while (c = getchar(), (c > '9' || c < '0') && c != '-')
    ;
  for ((c == '-' ? sg = 1, c = getchar() : 0), first = 0; c >= '0' && c <= '9';
       c = getchar())
    first = (first << 1) + (first << 3) + c - '0';
  if (sg) first = -first;
}
template <class T, class T1>
inline void gn(T &first, T1 &second) {
  gn(first);
  gn(second);
}
template <class T, class T1, class T2>
inline void gn(T &first, T1 &second, T2 &z) {
  gn(first);
  gn(second);
  gn(z);
}
template <typename T>
inline void print(T first) {
  if (first < 0) {
    putchar('-');
    return print(-first);
  }
  if (first < 10) {
    putchar('0' + first);
    return;
  }
  print(first / 10);
  putchar(first % 10 + '0');
}
template <typename T>
inline void println(T first) {
  print(first), putchar('\n');
}
template <typename T>
inline void printsp(T first) {
  print(first), putchar(' ');
}
template <class T, class T1>
inline void print(T first, T1 second) {
  printsp(first), println(second);
}
template <class T, class T1, class T2>
inline void print(T first, T1 second, T2 z) {
  printsp(first), printsp(second), println(z);
}
int power(int a, int b, int m, int ans = 1) {
  for (; b; b >>= 1, a = (long long)a * a % m)
    if (b & 1) ans = (long long)ans * a % m;
  return ans;
}
pair<int, int> p[50010];
int f[50010];
void go(int first) {
  printf("? %d\n", first);
  fflush(stdout);
  gn(p[first].first, p[first].second);
}
void end(int first) {
  printf("! %d\n", first);
  exit(0);
}
int main() {
  int n, id, first;
  gn(n, id, first);
  for (int i = 1; i <= n; i++) f[i] = i;
  srand(time(0));
  random_shuffle(f + 1, f + n + 1);
  go(id);
  if (p[id].first >= first) end(p[id].first);
  int N = min(n, 1000);
  for (int i = 1; i <= N; i++) {
    go(f[i]);
    int u = p[f[i]].first;
    if (u < first && u > p[id].first) id = f[i];
  }
  while (1) {
    if (!p[id].second) go(id);
    if (p[id].first >= first) end(p[id].first);
    if (p[id].second == -1) end(-1);
    id = p[id].second;
  }
}
