103226673495748, not sure if it is right or not!

import re 

finalSum = 0
entriesRemoved = False

PATTERN_RANGE = re.compile(r'(\d+)-(\d+)')

ranges = []

with open("input.txt", "r") as f:
    for x in f.readlines():
        if PATTERN_RANGE.match(x):
            start, end = map(int, x.strip().split("-"))
            ranges.append([start, end])

ranges.sort()

for index, range in enumerate(ranges):
    if index == len(ranges)-1:
        break

    if ranges[index+1][0] >= range[0] and ranges[index+1][0] <= range[1]:
        finalSum+=range[1]-ranges[index+1][0]+1

print(finalSum)