func_code_string: #include <bits/stdc++.h>   #pragma GCC optimize( -O3 )   #pragma GCC optimize( Ofast )   #pragma GCC optimize( unroll-loops )   using namespace std;   const long long MAXN = 1123456;   const long long N = 2e6;   const long long inf = 3e18;   const long long mod = 998244353;   const long long MOD = mod * (mod - 2);   mt19937_64 rnd(chrono::system_clock::now().time_since_epoch().count());   template <typename T>   void vout(T s) {     cout << s << endl;     exit(0);   }   void main_solve() {     long long n;     cin >> n;     vector<long long> a(n + 1);     for (int i = 1; i <= n; i++) cin >> a[i];     vector<bool> f(n + 1);     vector<long long> c, ans;     long long s = 1;     while (1) {       c.push_back(s);       if (f[s]) break;       f[s] = 1;       s = s - a[s];     }     reverse(c.begin(), c.end());     ans.push_back(c[0]);     for (int i = 1; i < (int)c.size(); i++)       if (c[i] != c[0]) {         ans.push_back(c[i]);       } else         break;     cout << (int)ans.size() <<   n ;     for (auto i : ans) cout << i <<    ;     cout <<   n ;   }   int main() {     ios_base ::sync_with_stdio(0);     cin.tie(0);     long long t;     cin >> t;     while (t--) {       main_solve();     }     return 0;   }   