Problem Statement

We have N cards numbered 1 to N. Each side of each card has a color represented by a positive integer.
One side of Card i has a color a_i, and the other side has a color b_i.
For each card, you can choose which side shows up. Find the maximum possible number of different colors showing up.

Input

Input is given from Standard Input in the following format:
N
a_1 b_1
a_2 b_2
:
a_N b_N

Output

Print the answer.

Constraints

• $1 \leq N \leq 200000$
• $1 \leq a_i,b_i \leq 400000$
• All numbers in input are integers.

Sample Input 1

4
1 2
1 3
4 2
2 3

Sample Output 1

4

We can choose the sides with 1, 3, 4, 2 to have four colors.

Sample Input 2

2
111 111
111 111

Sample Output 2

1

They are painted with just one color.

Sample Input 3

12
5 2
5 6
1 2
9 7
2 7
5 5
4 2
6 7
2 2
7 8
9 7
1 8

Sample Output 3

8

见题面 Input 部分

见题面 Output 部分