public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  int m = sc . nextInt ( ) ;
  int k = sc . nextInt ( ) ;
  int [ ] h = new int [ n + 1 ] ;
  for ( int i = 0 ;
  i < m ;
  i ++ ) h [ sc . nextInt ( ) ] ++ ;
  int i = 0 , pos = 1 , u , v ;
  while ( i < k ) {
    i ++ ;
    u = sc . nextInt ( ) ;
    v = sc . nextInt ( ) ;
    if ( h [ pos ] > 0 ) continue ;
    if ( u != pos && v != pos ) continue ;
    pos = pos != u ? u : v ;
  }
  System . out . println ( pos ) ;
  sc . close ( ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; int m = sc . nextInt ( ) ; int k = sc . nextInt ( ) ; int [ ] h = new int [ n + 1 ] ; for ( int i = 0 ; i < m ; i ++ ) h [ sc . nextInt ( ) ] ++ ; int i = 0 , pos = 1 , u , v ; while ( i < k ) { i ++ ; u = sc . nextInt ( ) ; v = sc . nextInt ( ) ; if ( h [ pos ] > 0 ) continue ; if ( u != pos && v != pos ) continue ; pos = pos != u ? u : v ; } System . out . println ( pos ) ; sc . close ( ) ; }
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