#include <iostream>
#include <fstream>

using namespace std;

int n=0,m=0,x=0,y=0,kkt=0,k=0,viz[1001];
bool a[1001][1001];

void dfs(int i,int kkt)
{
    if(viz[i]==0)
    {
        viz[i]=kkt;
        for(int j=1;j<=n;j++)
        {
            if(viz[j]==0 && a[i][j]==1)
                dfs(j,kkt);
        }
    }
}
int main()
{
    int i;
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);
    cin>>n>>m;
    for(i=1;i<=m;i++)
    {
        cin>>x;
        cin>>y;
        a[x][y]=1;
        a[y][x]=1;
    }
    kkt=1;
    dfs(1,kkt);
    for(i=1;i<=n;i++)
    {
        if(viz[i]==kkt) k++;
    }
    cout<<k<<"\n";
    return 0;
}