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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
class UnionFind {
private:
  vector<int> a;

public:
  int siz;
  UnionFind(int x) : a(x, -1), siz(x) {}

  int root(int x) {
    return a[x] < 0 ? x : a[x] = root(a[x]);
  }

  void unite(int x, int y) {
    x = root(x);
    y = root(y);
    if (x == y) return;
    siz--;
    if (a[x] > a[y]) swap(x, y);
    a[x] += a[y];
    a[y] =x;
  }

  bool same(int x, int y) {
    return root(x) == root(y);
  }

  int size(int x) {
    return -a[root(x)];
  }
};
signed main() {
  ios::sync_with_stdio(false); cin.tie(0);
  int n, m;
  cin >> n >> m;
  UnionFind uf(n);
  for (int i = 0; i < m; i++) {
    int x, y, z;
    cin >> x >> y >> z;
    uf.unite(--x, --y);
  }
  cout << uf.siz << endl;
  return 0;
}