#include <fstream>
#include <vector>
using namespace std;

ifstream cin ("dfs.in");
ofstream cout ("dfs.out");

vector<int> g[100001];
int viz[100001];

void dfs(int x)
{
    viz[x] = 1;
    for (int i = 0; i < g[x].size(); i++)
    {
        if (viz[g[x][i]] == 0)
        {
            dfs(g[x][i]);
        }
    }
}

int main()
{
    int n,m;
    cin >>n>>m;
    for (int i = 1; i <= m; i++)
    {
        int x,y;
        cin >>x>>y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    dfs(1);
    int rez = 0;
    for (int i = 1; i <= n; i++)
    {
        rez += viz[i];
    }
    cout <<rez;
    return 0;
}