# Enter your code here. Read input from STDIN. Print output to STDOUT
import heapq
import sys

for _ in range(int(sys.stdin.readline())):
    t = list(map(int, sys.stdin.readline().split()))
    n = t[0]
    if n == 0:
        print(0)
        continue
    a = sorted(t[1:])
    heap = {}
    for x in a:
        if x not in heap:
            heap[x] = []
        if x - 1 in heap and len(heap[x - 1]) > 0:
            heapq.heappush(heap[x], heapq.heappop(heap[x - 1]) + 1)
        else:
            heapq.heappush(heap[x], 1)
    print(min(heap[x][0] for x in heap if len(heap[x])))