Help me in solving AIRM problem

help
,
1

My issue

at thrid sample test case why we just require 1 runway?

My code

# cook your dish here
t = int(input())
for _ in range(t):
    n = int(input())
    arr = [int(i) for i in input().split()]
    dep = [int(i) for i in input().split()]
    l = 0
    r = 0
    c,m = 0,0
    while l < n:
        if arr[l] <= dep[r]:
            c += 1
            l += 1
        else:
            c -= 1
            r += 1
        m = max(m,c)
    print(m)

Problem Link: Airport Management Practice Coding Problem