func_code_string: #include <bits/stdc++.h>   void __check(const char* expr, const char* file, unsigned int line) {     printf( %s:%u: failed check `%s  n , file, line, expr);     abort();   }   using namespace std;   template <typename T>   bool uin(T& a, T b) {     if (b < a) {       a = b;       return true;     }     return false;   }   template <typename T>   bool uax(T& a, T b) {     if (a < b) {       a = b;       return true;     }     return false;   }   template <typename T>   int sz(const T& t) {     return static_cast<int>(t.size());   }   template <typename T>   void shrink(std::vector<T>& v) {     std::vector<T>(v).swap(v);   }   const bool DBG = false;   int main() {     ios_base::sync_with_stdio(false);     int n;     cin >> n;     vector<int> v(1 + n);     for (int i = 0; i < (int)(n); ++i) {       cin >> v[i];       v[i]--;     }     v[n] = v[n - 1] ^ 1;     int prev = v[0];     array<int, 2> a;     a.fill(0);     a[prev]++;     int res = 0;     for (int i = 1; i <= n; ++i) {       int value = v[i];       if (value != prev) {         if (a[value] > 0) {           int opposite = value ^ 1;           auto local_res = min(a[opposite], a[value]) * 2;           res = max(local_res, res);           a[value] = 0;         }       }       a[value]++;       prev = value;     }     cout << res << endl;     return 0;   }   