why does the last character disappear?

Question

The file contents are:

min:1,2,3,4,5,6
max:1,2,3,4,5,6
avg:1,2,3,4,5,6

Code:

def avg_calc():

    total = 0

    nums_inLine = line[4: -1]

    num_list = []

    num_list = nums_inLine.split(',')

    length = len(num_list)

    print(num_list)

with open('input.txt', 'r', encoding='utf-8-sig') as in_file:
    
    content = in_file.readlines()

    for line in content:

        if 'min' in line:
            
            min_calc()
            
        elif 'max' in line:

            max_calc()

        elif 'avg' in line:

            avg_calc()

My problem is that the '6' in the third line disappears or replaced by a whitespace. Why does it do that?

Output:

['1', '2', '3', '4', '5', '']

final goal is to cast each element in the list to an int then perform calculations to calculate the average of the numbers.