# Critical Wave

The task is simple. Through some critical points in 2D, you are to draw a wave like curve. Your goal is to include as many points as possible. • There will be an imaginary line y = a, which we call the major axis for the curve. • All the points on the curve should have different x coordinates. Their y coordinates should be of form a−1 or a+1. Two consecutive points on the curve should have a difference of 2 in their y coordinate Input There will be no more than 222 test cases. Each test case starts with an integer N, the number of points in the test case. In the next N lines, there will be N pair of integers giving the x and y coordinate of the points. There will be no more than 1000 points in each test case. All coordinates are integers – they’d fit in an signed 2 byte integer data type. Output For each test case print a number – the maximum number of critical points that can be included in a curve drawn from the given points. Sample Input 10 01 10 1 -1 2 -2 31 3 -1 3 -2

2/2 41 4 -1 5 -1 10 01 10 1 -1 2 -2 31 3 -1 3 -2 41 4 -1 5 -1 Sample Output 4 4