func_code_string: #include <bits/stdc++.h>   using namespace std;   int N;   vector<int> V;   bool Do() {     while (V.size() > 0 && V.back() % 2 == 0) V.pop_back();     if (V.size() == 0) return false;     int sum = 0;     int p = -1;     for (int i = 0; i < V.size(); ++i) {       if (V[i] % 2 && i < V.size() - 1) p = i;       sum += V[i];     }     if (sum % 2 == 0)       return true;     else if (p == -1)       return false;     else {       for (int i = p; i + 1 < V.size(); ++i) V[i] = V[i + 1];       V.pop_back();       return true;     }   }   int main() {     int nr_t, nr;     char c;     cin >> nr_t;     for (int i = 1; i <= nr_t; ++i) {       cin >> N;       for (int j = 1; j <= N; ++j) {         cin >> c;         V.push_back(c -  0 );       }       if (!Do())         cout <<  -1  <<   n ;       else {         for (int i = 0; i < V.size(); ++i) cout << V[i];         cout <<   n ;       }       V.clear();     }     return 0;   }   