func_code_string: #include <bits/stdc++.h>   #pragma GCC optimize( -O3 )   using namespace std;   const long long N = 1e6 + 5;   void pairsort(long long a[], long long b[], long long n) {     pair<long long, long long> pairt[n];     for (long long i = 0; i < n; i++) {       pairt[i].first = a[i];       pairt[i].second = b[i];     }     sort(pairt, pairt + n);     for (long long i = 0; i < n; i++) {       a[i] = pairt[i].first;       b[i] = pairt[i].second;     }   }   long long gcd(long long a, long long b) {     if (b == 0) return a;     return gcd(b, a % b);   }   long long isPrime(long long n) {     if (n < 2) return 0;     if (n < 4) return 1;     if (n % 2 == 0 or n % 3 == 0) return 0;     for (long long i = 5; i * i <= n; i += 6)       if (n % i == 0 or n % (i + 2) == 0) return 0;     return 1;   }   long long C(long long n, long long r) {     if (r > n - r) r = n - r;     long long ans = 1;     for (long long i = 1; i <= r; i++) {       ans *= n - r + i;       ans /= i;     }     return ans;   }   long long mod = 1e9 + 7;   long long modexpo(long long x, long long p) {     long long res = 1;     x = x % mod;     while (p) {       if (p % 2) res = res * x;       p >>= 1;       x = x * x % mod;       res %= mod;     }     return res;   }   struct pair_hash {     template <class T1, class T2>     std::size_t operator()(std::pair<T1, T2> const &pair) const {       std::size_t h1 = std::hash<T1>()(pair.first);       std::size_t h2 = std::hash<T2>()(pair.second);       return h1 ^ h2;     }   };   long long n, x, y, f[N], vis[N], a[N], k;   set<pair<long long, long long>, greater<pair<long long, long long>>> s;   int32_t main() {     ios::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     ;     cin >> n >> x;     for (long long i = 1; i <= n; i++) {       cin >> y, a[i] = y;       if (x == y)         f[x]++;       else {         s.erase({f[y], y}), f[y]++, s.insert({f[y], y});         pair<long long, long long> p = *s.begin();         if (p.first >= f[x]) k = 1;       }     }     if (!k) return cout << -1, 0;     memset(f, 0, sizeof(f));     unordered_set<pair<long long, long long>, pair_hash> ss;     for (long long i = 1; i <= 1e6; i++)       if (x != i) ss.insert({0, i});     for (long long i = 1; i <= n; i++) {       if (x == a[i]) {         f[x]++;         vector<long long> vv;         for (auto it = ss.begin(); it != ss.end(); it++)           if ((*it).first < f[x])             vv.push_back({(*it).second}), vis[(*it).second] = 1;         for (long long i = 0; i < vv.size(); i++) ss.erase({f[vv[i]], vv[i]});       } else if (!vis[a[i]])         ss.erase({f[a[i]], a[i]}), f[a[i]]++, ss.insert({f[a[i]], a[i]});     }     vector<long long> vv;     for (auto it = ss.begin(); it != ss.end(); it++)       if (vis[(*it).second]) vv.push_back((*it).second);     for (long long i = 0; i < vv.size(); i++) ss.erase({f[vv[i]], vv[i]});     if (!ss.size()) return cout << -1, 0;     cout << (*ss.begin()).second;     return 0;   }   