first_list = []
second_list = []
result = 0
with open("part1_input.txt", "r") as file_input:
    for row in file_input:
        first_column, second_column = map(int, row.split("   "))
        first_list.append(first_column)
        second_list.append(second_column)

first_list.sort()
second_list.sort()

for i in range(len(first_list)):
    result += abs(first_list[i] - second_list[i])

print(result)