public static void solve ( ) throws Exception {
  int n = f . ni ( ) ;
  int m = f . ni ( ) ;
  int dp [ ] = new int [ 105 ] ;
  for ( int i = 0 ;
  i < n ;
  ++ i ) {
    int l = f . ni ( ) ;
    int r = f . ni ( ) ;
    ++ dp [ l ] ;
    -- dp [ r + 1 ] ;
  }
  int cnt = 0 ;
  for ( int i = 1 ;
  i < 105 ;
  ++ i ) dp [ i ] += dp [ i - 1 ] ;
  ArrayList < Integer > ans = new ArrayList < > ( ) ;
  for ( int i = 1 ;
  i <= m ;
  ++ i ) {
    if ( dp [ i ] == 0 ) {
      ++ cnt ;
      ans . add ( i ) ;
    }
  }
  pn ( cnt ) ;
  for ( Integer x : ans ) p ( x + " " ) ;
}

public static void solve ( ) throws Exception { int n = f . ni ( ) ; int m = f . ni ( ) ; int dp [ ] = new int [ 105 ] ; for ( int i = 0 ; i < n ; ++ i ) { int l = f . ni ( ) ; int r = f . ni ( ) ; ++ dp [ l ] ; -- dp [ r + 1 ] ; } int cnt = 0 ; for ( int i = 1 ; i < 105 ; ++ i ) dp [ i ] += dp [ i - 1 ] ; ArrayList < Integer > ans = new ArrayList < > ( ) ; for ( int i = 1 ; i <= m ; ++ i ) { if ( dp [ i ] == 0 ) { ++ cnt ; ans . add ( i ) ; } } pn ( cnt ) ; for ( Integer x : ans ) p ( x + " ▁ " ) ; }
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