#include <cstdio>
#include <queue>

using namespace std;

struct graf{int v,m,adi[1000][1000];};

graf A;
queue<int> q;

int viz[1000];

void Read()
{
    int a,b;
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);
    scanf("%i %i",&A.v,&A.m);
    for(int i=1;i<=A.v;i++)
    {
        for(int j=1;j<=A.v;j++)
        {
            scanf("%i %i",&a,&b);
            A.adi[a][b]=A.adi[b][a]=1;
        }
    }
}

void Parcurgere(int nod)
{
    viz[nod] = 1;
    for(int i=1;i<=A.v;i++)
    {
        if(viz[i] == 0 && A.adi[nod][i] == 1)
            Parcurgere(i);
    }
}

int main()
{
    int k=1;
    Read();
    for(int i=1;i<=A.v;i++)
        if(viz[i]==0)
        {
            Parcurgere(i);
            k++;
        }
    printf("%i",--k);
    return 0;
}