Problem: SHUFFLIN , Contest: SEPT21C

#include <bits/stdc++.h>
using namespace std;
int main()
{
    int t;
    cin>>t;
    while (t--)
    {
        int n;
        cin >> n;
        vector<int> v;
        for (int i=0;i<n;i++)
        {
            int temp;
            cin>>temp;
            v.push_back(temp);
        }
        int o= 0; 
        int e= 0;
        for (int i=0;i<n;i++)
        {
            if ((i+ 1+v[i])%2==0)
            {
                if (v[i]%2==0)
                    e++;
                else
                    o++;
            }
        }
        int sol=0;
        sol = abs(e - o);
        sol = n-sol;
        cout<<sol<<endl;
    }
    return 0;
}