/**
 * Code by Patrick Sava
 * "Spiru Haret" National College of Bucharest
 **/

# include "fstream"
# include "cstring"
# include "vector"
# include "queue"
# include "bitset"
# include "algorithm"
# include "map"
# include "unordered_map"
# include "deque"
# include "string"
# include "iomanip"
# include "cmath"
# include "stack"
# include "cassert"

const char IN [ ] =  "dfs.in" ;
const char OUT [ ] = "dfs.out" ;
const int MAX = 100999 ;

# define pb push_back
# define mp make_pair
# define FORN( a , b , c ) for ( int a = b ; a <= c ; ++ a )
# define FORNBACK( a , b , c ) for ( int a = b ; a >= c ; -- a )

using namespace std ;

ifstream cin ( IN ) ;
ofstream cout ( OUT ) ;

vector < int > gr [ MAX ] ;

bitset < MAX > viz ;

inline void dfs ( int nod )
{
    viz [ nod ] = 1 ;
    for ( auto x : gr [ nod ] )
        if ( viz [ x ] == 0 )
            dfs ( x ) ;
}

int main()
{
    int n , m ;
    cin >> n >> m ;

    while ( m -- )
    {
        int x , y ;
        cin >> x >> y ;
        gr [ x ].pb ( y ) ;
        gr [ y ].pb ( x ) ;
    }
    int sol = 0 ;
    FORN ( i , 1 , n )
        if ( viz [ i ] == 0 )
        {
            dfs ( i ) ;
            ++ sol ;
        }
    cout << sol << '\n' ;
    return 0;
}