public static void main ( String [ ] args ) {
  FastScanner input = new FastScanner ( ) ;
  int n = input . nextInt ( ) ;
  int m = input . nextInt ( ) ;
  int k = input . nextInt ( ) ;
  TreeSet < Integer > set = new TreeSet < > ( ) ;
  for ( int i = 0 ;
  i < m ;
  i ++ ) {
    set . add ( input . nextInt ( ) ) ;
  }
  int start = 1 ;
  for ( int i = 0 ;
  i < k ;
  i ++ ) {
    int u = input . nextInt ( ) ;
    int v = input . nextInt ( ) ;
    if ( set . contains ( start ) ) {
      System . out . println ( start ) ;
      return ;
    }
    if ( start == u ) {
      start = v ;
    }
    else if ( start == v ) {
      start = u ;
    }
  }
  System . out . println ( start ) ;
}

public static void main ( String [ ] args ) { FastScanner input = new FastScanner ( ) ; int n = input . nextInt ( ) ; int m = input . nextInt ( ) ; int k = input . nextInt ( ) ; TreeSet < Integer > set = new TreeSet < > ( ) ; for ( int i = 0 ; i < m ; i ++ ) { set . add ( input . nextInt ( ) ) ; } int start = 1 ; for ( int i = 0 ; i < k ; i ++ ) { int u = input . nextInt ( ) ; int v = input . nextInt ( ) ; if ( set . contains ( start ) ) { System . out . println ( start ) ; return ; } if ( start == u ) { start = v ; } else if ( start == v ) { start = u ; } } System . out . println ( start ) ; }
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