def max_subarray_sum(arr):
    max_sum=float('-inf')
    curr_sum=0
    for num in arr:
        curr_sum=max(num,curr_sum+num)
        max_sum=max(max_sum,curr_sum)
    return max_sum
arr=[-2,1,-3,4,-1,2,1,-5,4]
print(max_subarray_sum(arr))