A Cycle of Points#6087
There are points on a plane, numbered from to . They form a directed cycle 1 \to 2 \to \ldots \to n \to 1. You need to perform the following operation several times: given the numbers of two points and , remove the part of the cycle starting with the point and ending with the point , and return it back in reversed order, so that part will start from and end with . Find the length of the final cycle.
The first line contains two numbers and (3 \leq n, m \leq 100000).
The next lines contain two numbers x_i and y_i — coordinates of the -th point.
The next lines contain two numbers a_i and b_i — point numbers in the -th operation.
Output the length of the final cycle with two digits after the decimal point.
Example 1
1. Initial cycle: 1 \to 2 \to 3 \to 4 \to 5 \to 1. 2. After the first operation: 1 \to 5 \to 3 \to 4 \to 2 \to 1 (part 5 \to 1 \to 2 is replaced with 2 \to 1 \to 5). 3. After the second operation: 1 \to 2 \to 4 \to 3 \to 5 \to 1 (part 5 \to 3 \to 4 \to 2 is replaced with 2 \to 4 \to 3 \to 5). 4. After the third operation: 1 \to 2 \to 5 \to 3 \to 4 \to 1.