import sys
input = sys.stdin.readline
from collections import *

def calc(A):
    dp = [0]*(N+1)
    
    for i in range(2, N):
        dp[i+1] = dp[i]
        
        if len({A[i-2], A[i-1], A[i]})==3:
            dp[i+1] = max(dp[i+1], dp[i-2]+A[i-2])
    
    return dp[N]

for _ in range(int(input())):
    N = int(input())
    A = deque(list(map(int, input().split())))
    ans = calc(A)
    A.append(A.popleft())
    ans = max(ans, calc(A))
    A.append(A.popleft())
    ans = max(ans, calc(A))
    print(ans)