Rectangle Area Union

Problem Description

There are $n$ rectangles $[X_{i,1}, X_{i,2}] \times [Y_{i,1}, Y_{i,2}]$ on the plane, i.e. rectangles whose lower-left corner is $(X_{i,1}, Y_{i,1})$ and upper-right corner is $(X_{i,2}, Y_{i,2})$. What is the area of their union?

Input Format

The first line contains an integer $n$ ($1\leq n\leq 2\times 10^5$).

The next $n$ lines each contain four integers $X_1, X_2, Y_1, Y_2$ ($1\leq X_1 \leq X_2 \leq 10^9,\ 1\leq Y_1 \leq Y_2 \leq 10^9$).

Note: empty rectangles may be present.

Output Format

Output one number, the answer.

Sample Input

2
1 4 2 3
2 3 1 4

Sample Output

5