1. Alexa has recently found N building blocks in the shape of a cylinder

   Each block has a radius and a height. She wants to build a fence by stacking some of those building blocks one over the other in any order she wants

   In order to put block X over block Y, radius and height of X should be strictly smaller than Y

   Your task is to find Maximum height of fence she can build. return answer in modulo 10 ** 9 + 7

   Example:
   N --> 3
   Radius --> 1 2 3
   Height --> 1 3 2

   OUTPUT
   4
   EXPLAINATION
   To get Maximum height use blocks 1 and 2

Example:

3
1 1 1
2 3 5
OUTPUT: 5

Use only block 3, as you cant stack any other block over other

Example:

2
4 1
3 7
OUTPUT: 7

Use block 2