import sys
input = sys.stdin.read

def main():
    data = input().split()
    index = 0
    T = int(data[index])
    index += 1
    results = []
    
    for _ in range(T):
        n = int(data[index])
        index += 1
        a = [0] * (n + 1)
        
        for i in range(1, n + 1):
            a[i] = int(data[index])
            index += 1
            a[i] += a[i - 1]
        
        ans = -10**18
        min1 = 0
        min2 = 10**18
        
        for i in range(1, n + 1):
            if i % 2 == 1:
                min1 = min(min1, a[i - 1])
            else:
                min2 = min(min2, a[i - 1])
            
            if i % 2 == 1:
                ans = max(ans, a[i] - min1)
            else:
                ans = max(ans, a[i] - min2)
        
        results.append(ans)
    
    for result in results:
        print(result)

if __name__ == "__main__":
    main()