Interval Summation

Write a program that takes a list of intervals and calculates the total length of all intervals after merging overlapping ones. Each interval is defined by a start and end time. The output should be the total length of all merged intervals. Input format: - The first line contains an integer n, the number of intervals. - Each of the next n lines contains two integers, start and end, separated by a space. Output format: - Print the total length as an integer. Example: Input: 4 1 4 2 5 7 9 8 10 Output: 7