5472: Meta-universe
内存限制：256 MB
时间限制：2 S
标准输入输出
题目类型：传统
评测方式：文本比较
上传者：
提交：1
通过：1
题目描述
F. meta-universe
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
Consider infinite grid of unit cells. Some of those cells are planets.
meta-universe M={p1,p2,...,pk} is a set of planets. Suppose there is an infinite row or column with following two properties: 1) it doesn't contain any planet pi of meta-universe M on it; 2) there are planets of M located on both sides from this row or column. In this case we can turn the meta-universe M into two non-empty meta-universes M1 and M2 containing planets that are located on respective sides of this row or column.
A meta-universe which can't be split using operation above is called a universe. We perform such operations until all meta-universes turn to universes.
Given positions of the planets in the original meta-universe, find the number of universes that are result of described process. It can be proved that each universe is uniquely identified not depending from order of splitting.
me
A me
Given positions of the planets in the original me
Input
The first line of input contains an integer n, (1≤n≤105), denoting the number of planets in the meThe next n lines each contain integers xi and yi, (-109≤xi,yi≤109), denoting the coordinates of the i-th planet. All planets are located in different cells.
Output
Print the number of resulting universes.
Examples
Input
5 0 0 0 2 2 0 2 1 2 2
Output
3
Input
8 0 0 1 0 0 2 0 3 3 0 3 1 2 3 3 3
Output
1
Note
The following figure describes the first test case: 
输入样例 复制
输出样例 复制