Why my code is not giving output?

[abdalimran]

Why the code i not giving output?

#include <bits/stdc++.h>
#define endl '\n'

using namespace std;

int co(int *ar,int n,int u, int v)
{
    int c=0;
    for(int i=u; i<=v; i++)
    {
        if(ar[u]==n)
            c++;
    }
    return c;
}

int main()
{
    ios::sync_with_stdio(false);cin.tie(0);

    int t;
    cin>>t;

    for(int i=1; i<=t; i++)
    {
        int n;
        cin>>n;

        int ar[n];

        for(int i=1; i<=n; i++)
            cin>>ar[i];

        int r;
        cin>>r;

        while(r--)
        {
            int u,v,c,sum=0;
            cin>>u>>v;

            for(int i=u; i<=v;i++)
            {
                c=co(ar,ar[i],u,v);

                if(c%2==1)
                    sum++;
            }
            cout<<sum<<endl;
        }
    }

    return 0;
}

[ne555]

undefined behaviour in the loop of line 31 (out of bounds access)
also possible in line 44


It would help the testing if you provide an example input.