#include <bits/stdc++.h>
#define MAXN 100005
#define For(I,A,B) for(int I = (A), endi = (B); I <= endi; ++I)
#define foR(I,A,B) for(int I = (A), endi = (B); I >= endi; --I)
#define ForE(I,A) for(int I = head[A]; I; I = e[I].nxt)
using namespace std;
typedef long long _ll;
typedef unsigned int ui;

int T,n,x;
_ll sum,ans;
void solve()
{
    cin >> n; set<_ll> s[2]; s[0].insert(0); ans = -0x7ffffffffffll;
    For(i,1,n)
    {
        cin >> x;
        sum += x; s[i&1].insert(sum);
        int p = !(i&1);
        if(s[p].empty()) continue;
        ans = max(ans,sum - *s[p].begin());
    }
    cout << ans << '\n';
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    cin >> T;
    while(T--) solve();
    return 0;
}