#include<fstream>
#include<vector>
using namespace std;
ifstream in ("dfs.in" );
ofstream out("dfs.out");
vector<int>ha[100000];
int v[100001],hz[10001];
int n,m,i,st,dr,a,b;
int main(){
    in >> n;
    in >> m;
    for( i = 1; i <= m; i ++ ){
        in >> a >> b;
        ha[a].push_back(b);
        ha[b].push_back(a);
    }
    v[1] = 1;
    hz[1] = 1;
        for( st = 1,dr = 1; st <= dr; st ++ ){
            for( i = 0; i <= ha[v[st]].size()-1; i ++ ){
                if( hz[ ha[v[st]][i] ] == 0 ){
                    dr ++;
                    v[dr] = ha[v[st]][i];
                    hz[ha[v[st]][i] ] = 1;
                }
            }
        }
    out<<dr;
    return 0;
}