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 JavaScript (node.js v5.12) (judge verdict: Accepted)

"use strict";
function I(t,i){this._s=t.split("\n"),this._c=0,this._l=0,this._f=i||Number}I.prototype.a=function(t){var i=this._s[this._l];if(i){var s=i.trim().split(" "),h=s[this._c];return this._c++,s.length===this._c&&(this._c=0,this._l++),t?t(h):this._f(h)}},I.prototype.l=function(t){var i=this._s[this._l];if(i)return this._c=0,this._l++,i.split(" ").map(t||this._f)},module.exports=I;
function Queue(e){this._queue=e?e.slice():[],this._tail=this._queue.length,this._head=0,this._maxLength=100000}Queue.prototype.enqueue=function(e){this._tail+1===this._head||0===this._head&&this._tail===this._maxLength-1?console.error("===queue overflow==="):(this._queue[this._tail]=e,this._tail+=1,this._tail===this._maxLength&&(this._tail=0))},Queue.prototype.dequeue=function(){if(this._tail!==this._head){var e=this._queue[this._head];return this._head+=1,this._head===this._maxLength&&(this._head=0),e}console.error("===queue underflow===")},Queue.prototype.size=function(){var e=this._tail-this._head;return e<0&&(e+=this._maxLength),e};

function main(input) {
  var o = new I(input);

  var n = o.a();
  var m = o.a();

  var x = [], y = [], z = [];
  for (var i = 0; i < m; i++) {
    x.push(o.a());
    y.push(o.a());
    z.push(o.a());
  }

  var adj = [];
  for (var i = 1; i <= n; i++) {
    adj[i] = [];
  }

  for (var i = 0; i < m; i++) {
    adj[x[i]].push(y[i]);
    adj[y[i]].push(x[i]);
  }
  
  var count = 0;
  var color = [];
  for (var i = 1; i <= n; i++) {
    if (color[i] === undefined) {
      color[i] = 1;
      bfs(i, color, adj);
      count += 1;
    }
  }
  console.log(count);
}

function bfs(i, color, adj) {
  var queue = new Queue();
  queue.enqueue(i);
  while (queue.size() > 0) {
    var cur = queue.dequeue();
    adj[cur].forEach(v => {
      if (color[v] === undefined) {
        color[v] = 1;
        queue.enqueue(v);
      }
    })
  }
}


main(require("fs").readFileSync("/dev/stdin", "utf8"));