Help me in solving TRACE problem

help
,
1

My issue

My code

# cook your dish here
for i in range(int(input())):
    n=int(input())
    arr=[]
    for i in range(n):
        li=[int(i) for i in input().split()]
        arr.append(li)
    ch=[]
    #ch[0]=arr[0][0]
    for i in range(0,n-1):
        for j in range(0,n-1):
            ch.append(arr[i][j]+arr[i+1][j+1])
    print(max(ch))

Problem Link: TRACE Problem - CodeChef