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

using namespace std;

#define NOT_VIS -1
#define VIS      1

struct Node{
    int dist;
    list<int> neigh;

    Node(){
        dist = NOT_VIS;
    }
};

vector<Node> nodes;

void DFS(int cnode){

    nodes[cnode].dist = VIS;

    list<int>::iterator it;

    for(it = nodes[cnode].neigh.begin();
        it != nodes[cnode].neigh.end();
        it ++){

        if(nodes[*it].dist == NOT_VIS){
            DFS(*it);
        }
    }
}

int main(){

    int N, M, S;
    int i,u,v;



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

    in >> N >> M >> S;

    nodes.resize(N+1);

    for(i = 0; i < M; i++){
        in >> u >> v;
        nodes[u].neigh.push_back(v);
        nodes[v].neigh.push_back(u);
    }


    int counter = 0;
    for(i = 1; i <= N; i++){
        if(nodes[i].dist == NOT_VIS){
            counter ++;
            DFS(i);
        }
    }

    out<<counter<<endl;

    in.close();
    out.close();

    return 0;
}