func_code_string: #include <bits/stdc++.h>   using namespace std;   mt19937 rd(chrono ::steady_clock ::now().time_since_epoch().count());   long long Rand(long long l, long long h) { return l + rd() % (h - l + 1); }   template <typename T>   inline void read(T &x) {     register char c;     bool sign = 0;     for (c = getchar(); !isdigit(c); c = getchar())       if (c ==  - ) sign = !sign;     x = c -  0 ;     for (c = getchar(); isdigit(c); c = getchar()) x = x * 10 + c -  0 ;     if (sign) x = -x;   }   template <typename T>   inline bool mini(T &x, T y) {     if (x > y)       x = y;     else       return 0;     return 1;   }   template <typename T>   inline bool maxi(T &x, T y) {     if (x < y)       x = y;     else       return 0;     return 1;   }   template <typename T>   inline void _abs(T &x) {     if (x < 0) x = -x;     return;   }   const int N = 1003;   int a[N];   int d[2];   int main() {     ios ::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     int t;     cin >> t;     while (t--) {       int n;       cin >> n;       for (int i = 1; i <= n; ++i) cin >> a[i];       d[0] = d[1] = 0;       for (int i = 1; i <= n; ++i) d[a[i]]++;       bool t;       if (d[0] < d[1])         t = 1;       else         t = 0;       vector<int> res;       for (int i = 1; i <= n; ++i)         if (a[i] == t) res.push_back(t);       if (t && (int)(res.size()) % 2) res.pop_back();       cout << res.size() <<   n ;       for (int x : res) cout << x <<    ;       cout <<   n ;     }     return 0;   }   