#include<vector>
#include<fstream>
#include<queue>

using namespace std;
const int MaxN=100005;
vector <int> v[MaxN];
ifstream fin ("dfs.in");
ofstream fout ("dfs.out");
int s,n,m,i,x,y,viz[MaxN],k;
queue<int> q;

void dfs(int nod)
{
    if(!viz[nod]){
        viz[nod]=k;
        for(int i=0;i<v[nod].size();++i)
        {
            if(!viz[v[nod][i]])
            {
                dfs(v[nod][i]);
            }
        }
    }
}

int main()
{

    fin>>n>>m>>s;
    for(i=1;i<=m;i++){
        fin>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }

    k=0;
    for(register int i=1;i<=n;++i)
    {
        if(!viz[i]){
            k++;
            dfs(i);
        }
    }

    fout<<k;
    fin.close();
    fout.close();
return 0;
}