Help me in solving DSSA67 problem

help
,
1

My issue

Time limit exceeded

My code

t = int(input())
for _ in range(t):
    n = int(input())
    G = list(map(int, input().split()))
    
    # initialise a counter to store max goal difference
    max_diff = 0
    
    i = 0
    
    while i < n:
        # For each possible i, j - find the max goal difference possible
        j = i + 1
        while j < n:
            if G[j] - G[i] > max_diff:
                max_diff = G[j] - G[i]
            j = j + 1
        i = i + 1
    
    if max_diff >= 1:
        print(max_diff)
    else:
        print('UNFIT')

Learning course: Kalasalingam Academy of Research and Education
Problem Link: CodeChef: Practical coding for everyone