from sys import stdin
input = stdin.readline

def func(n, C, cnt):
    for i in reversed(range(n, N*2+10)):
        cnt += C[i]
        C[i] = 0
    right = 0
    for i in range(n):
        if right == i:
            right += 1
        if 1 <= C[i]:
            rem = C[i]-1
            C[i] = 1
            if 1 <= i:
                cnt += rem*(1<<(i-1))
            else:
                cnt += rem
        else:
            if 1 <= i:
                cost = 1<<(i-1)
            else:
                cost = 1
            if cost <= cnt:
                cnt -= cost
                C[i] = 1
            else:
                cost -= cnt
                cnt = 0
                while 1 <= cost and right < N*2+10:
                    if 1 <= C[right]:
                        cost -= 1
                        C[right] -= 1
                    if C[right] == 0:
                        right += 1
                if cost == 0:
                    C[i] = 1
                else:
                    return False
    return True

for _ in range(int(input())):
    N = int(input())
    A = list(map(int, input().split()))

    C = [0]*(N*2+10)
    cnt = 0
    for a in A:
        if a < N*2+10:
            C[a] += 1
        else:
            cnt += 1

    left = 0
    right = N*3
    while left+1 < right:
        mid = (left+right)//2
        if func(mid, C[:], cnt):
            left = mid
        else:
            right = mid

    print(left)