miyagi-sensei/merge_intervals

Merge Intervals

Merge Intervals

In this exercise your job is to merge the intervals, where some of them possibly overlapping.

Inputs

The first line consists of 1 integer N.
The next N lines each contains 2 numbers, L and R, representing an interval {L, R} with length R - L + 1. (1 ≤ L ≤ R ≤ 2 𝖷 10<sup>9)

Outputs

The length of discrete boxes covered by the intervals.

Sample Tests

Input 1

7
1 1
1 2
1 3
1 5
2 3
1 8
2 8

Output 1

8

Subtasks

For all cases:
1 <= N <= 1 𝖷 10⁸

#	Points	Constraints
1	50	N <= 1 𝖷 104
2	50	no additional constraint