Problem:
Score : 500 points

Problem Statement

There are N cards placed face down in a row. On each card, an integer 1 or 2 is written.

Let A_i be the integer written on the i-th card.

Your objective is to guess A_1, A_2, ..., A_N correctly.

You know the following facts:

For each i = 1, 2, ..., M, the value A_{X_i} + A_{Y_i} + Z_i is an even number.

You are a magician and can use the following magic any number of times:

Magic: Choose one card and know the integer A_i written on it. The cost of using this magic is 1.

What is the minimum cost required to determine all of A_1, A_2, ..., A_N?

It is guaranteed that there is no contradiction in given input.

Constraints

All values in input are integers.

2 \leq N \leq 10^5

1 \leq M \leq 10^5

1 \leq X_i < Y_i \leq N

1 \leq Z_i \leq 100

The pairs (X_i, Y_i) are distinct.

There is no contradiction in input. (That is, there exist integers A_1, A_2, ..., A_N that satisfy the conditions.)

Input

Input is given from Standard Input in the following format:

N M
X_1 Y_1 Z_1
X_2 Y_2 Z_2
\vdots
X_M Y_M Z_M

Output

Print the minimum total cost required to determine all of A_1, A_2, ..., A_N.

Sample Input 1

3 1
1 2 1

Sample Output 1

2

You can determine all of A_1, A_2, A_3 by using the magic for the first and third cards.

Sample Input 2

6 5
1 2 1
2 3 2
1 3 3
4 5 4
5 6 5

Sample Output 2

2

Sample Input 3

100000 1
1 100000 100

Sample Output 3

99999

Solution in Rust (1.15.1) (judge verdict: Wrong Answer)

// #[warn(dead_code)]
// const TOP: u64 = 1000000007;

fn main() {
	let text = {
		use std::io::Read;
		let mut s = String::new();
		std::io::stdin().read_to_string(&mut s).unwrap();
		s
	};

	let mut iter = text.split_whitespace();
	let num: usize = iter.next().unwrap().parse().unwrap();
	let linelen: usize = iter.next().unwrap().parse().unwrap();

	use std::collections::HashMap;

	let mut colors: HashMap<u64, u32> = HashMap::new();

	// let mut map: HashMap<u64, HashMap<u64, bool>> = HashMap::new();

	let mut idx: u32 = 0;

	for _ in 0..linelen {
		let u: u64 = iter.next().unwrap().parse().unwrap();
		let v: u64 = iter.next().unwrap().parse().unwrap();
		let _: usize = iter.next().unwrap().parse().unwrap();
		// let b = w % 2 == 0;
		// let mut done = false;
		// colors.entry(u).or_insert(i);
		if let Some(&c) = colors.get(&u) {
			if let Some(&c2) = colors.get(&v) {
				for j in 1..(num + 1) {
					let j = j as u64;
					if let Some(&c3) = colors.get(&j) {
						if c3 == c2 {
							colors.insert(j, c);
						}
					}
				}
			} else {
				colors.insert(v, c);
			}
		} else {
			if let Some(&c) = colors.get(&v) {
				colors.insert(u, c);
			} else {
				colors.insert(u, idx);
				colors.insert(v, idx);
				idx += 1;
			}
		}
	}

	for i in 1..(num + 1) {
		let i = i as u64;
		if let None = colors.get(&i) {
			idx += 1;
		}
	}

	println!("{}", idx);
}