public static void main ( String [ ] args ) {
  FastScanner input = new FastScanner ( ) ;
  int n = input . nextInt ( ) ;
  int m = input . nextInt ( ) ;
  ArrayList < ArrayList < Integer >> a = new ArrayList < > ( n + 1 ) ;
  boolean visited [ ] = new boolean [ n + 1 ] ;
  for ( int i = 0 ;
  i <= n ;
  i ++ ) {
    a . add ( new ArrayList < > ( ) ) ;
  }
  for ( int i = 0 ;
  i < m ;
  i ++ ) {
    int x = input . nextInt ( ) ;
    int y = input . nextInt ( ) ;
    a . get ( x ) . add ( y ) ;
    a . get ( y ) . add ( x ) ;
  }
  long ans = 0 ;
  for ( int i = 1 ;
  i <= n ;
  i ++ ) {
    if ( ! visited [ i ] ) {
      count = 0 ;
      dfs ( visited , a , i ) ;
      ans += ( count - 1 ) ;
    }
  };
}

public static void main ( String [ ] args ) { FastScanner input = new FastScanner ( ) ; int n = input . nextInt ( ) ; int m = input . nextInt ( ) ; ArrayList < ArrayList < Integer > > a = new ArrayList < > ( n + 1 ) ; boolean visited [ ] = new boolean [ n + 1 ] ; for ( int i = 0 ; i <= n ; i ++ ) { a . add ( new ArrayList < > ( ) ) ; } for ( int i = 0 ; i < m ; i ++ ) { int x = input . nextInt ( ) ; int y = input . nextInt ( ) ; a . get ( x ) . add ( y ) ; a . get ( y ) . add ( x ) ; } long ans = 0 ; for ( int i = 1 ; i <= n ; i ++ ) { if ( ! visited [ i ] ) { count = 0 ; dfs ( visited , a , i ) ; ans += ( count - 1 ) ; } } ; }
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