Comment: Amazon OA - Set 3 - Oncampus 2022

#include using namespace std; int main() { int n; cin>>n; vector v(n); int x; map m; for(int i=0;i>x; m[x]++; } int res = 0; for(auto itr:m){ if (itr.second == 1){ cout<<"-1"; break; } else{ int y = itr.second / 2; res += 2*(y/3) + (y%3); } } cout<<res; return 0; }