#include <bits/stdc++.h>

using i64 = long long;

void solve() {
int n;
std::cin >> n;

std::vector<int> c(n);
for (int i = 0; i < n; i++) {
std::cin >> c[i];
}

i64 ans = -1E18;
for (int t = 0; t < 2; t++) {
i64 sum = 0;
int mx = -1E9;
for (int i = t; i < n; i += 2) {
if (c[i] > 0) {
sum += c[i];
}
mx = std::max(mx, c[i]);
}
if (sum == 0) {
sum = mx;
}
ans = std::max(ans, sum);
}

std::cout << ans << "\n";
}

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

int t;
std::cin >> t;

while (t--) {
solve();
}

return 0;
}