#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#define N 100000
#define M 200000

typedef struct
{
    int vf, urm;
} element;

int cc[N+1], lst[N+1], n, m, nr, ncc, stiva[N+1];
element v[2*M+1];

void adauga(int x, int y)
{//adauga pe y in lista de adiacenta a lui x
    v[++nr].vf = y;
    v[nr].urm = lst[x];
    lst[x] = nr;
}

void push(int *pvf, int val)
{
    stiva[++(*pvf)] = val;
}

void pop(int *pvf)
{
    --(*pvf);
}

bool empty(int vf)
{
    return (vf == 0);
}

int primul_vecin_nevizitat(int x)
{
    while (lst[x] != 0 && cc[v[lst[x]].vf] != 0)//caut primul vecin al lui x cu cc nul
    {
        lst[x] = v[lst[x]].urm;
    }
    if (lst[x] != 0)
    {
        int y = v[lst[x]].vf;
        lst[x] = v[lst[x]].urm;
        return y;
    }
    return 0;
}

void dfs_it(int x)
{
    int vf_stiva = 0;
    cc[x] = ncc;
    push(&vf_stiva, x);
    while (!empty(vf_stiva))
    {
        x = stiva[vf_stiva];
        int y = primul_vecin_nevizitat(x);
        if (y == 0)
        {
            pop(&vf_stiva);
        }
        else
        {
            cc[y] = ncc;
            push(&vf_stiva, y);
        }
    }
}

int main()
{
    FILE *in, *out;
    in = fopen("dfs.in", "r");
    out = fopen("dfs.out", "w");
    fscanf(in, "%d%d", &n, &m);
    for (int i = 0; i < m; i++)
    {
        int x, y;
        fscanf(in, "%d%d", &x, &y);
        adauga(x, y);
        adauga(y, x);
    }
    for (int i = 1; i <= n; i++)
    {
        if (cc[i] == 0)
        {
            ++ncc;
            dfs_it(i);
        }
    }
    fprintf(out, "%d", ncc);
    fclose(in);
    fclose(out);
    return 0;
}