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 (GCC 9.2.1) (judge verdict: Runtime Error)

#include <stdio.h>
#include <stdlib.h>

typedef struct List
{
    struct List *next;
    int i;
} list;

void queue(list *p, int i)
{
    if (p->next == NULL)
    {
        p->next = (list *)malloc(sizeof(list));
        (p->next)->i = i;
        (p->next)->next = NULL;
        return ;
    }
    queue(p->next, i);
}

void queue2(list *p, list *q)
{
    if (p->next == NULL)
    {
        while (q->next)
        {
            p->next = (list *)malloc(sizeof(list));
            (p->next)->i = q->i;
            p = p->next;
            q = q->next;
        }
        p->next = NULL;
    }
    queue(p->next, q);
}

void input(int *f, list *l, int i)
{
    while (l->next)
    {
        f[l->i] = i;
        l = l->next;
    }
}

int main(void){
    int n, m, x[100001], y[100001], z[1], f[100001] = {}, i, ii, cnt = 0;
    list l[100001];
    scanf("%d%d", &n, &m);
    for (i = 0; i < m; i++)
        scanf("%d%d%d", x + i, y + i, z);
    for (i = 0; i < m; i++)
    {
        if (f[x[i]] + f[y[i]] == 0)
        {
            f[x[i]] = i + 1;
            f[y[i]] = i + 1;
            cnt++;
            l[i].i = x[i];
            l[i].next = (list *)malloc(sizeof(list));
            (l[i].next)->i = y[i];
            (l[i].next)->next = NULL;
        }
        else if (f[x[i]] && !f[y[i]])
        {
            f[y[i]] = f[x[i]];
            cnt++;
            queue(&l[f[x[i]]], y[i]);
        }
        else if (!f[x[i]] && f[y[i]])
        {
            f[x[i]] = f[y[i]];
            cnt++;
            queue(&l[f[x[i]]], x[i]);
        }
        else if (f[x[i]] - f[y[i]])
        {
            cnt++;
            queue2(&l[f[x[i]]], &l[f[y[i]]]);
            input(f, &l[f[x[i]]], f[x[i]]);
        }
    }
    printf("%d", n - cnt);
}