public static void main ( String [ ] args ) throws IOException {
  BufferedReader reader = new BufferedReader ( new InputStreamReader ( System . in ) ) ;
  String [ ] tmp = reader . readLine ( ) . split ( " " ) ;
  int n = Integer . valueOf ( tmp [ 0 ] ) ;
  int m = Integer . valueOf ( tmp [ 1 ] ) ;
  int x = Integer . valueOf ( tmp [ 2 ] ) ;
  int y = Integer . valueOf ( tmp [ 3 ] ) ;
  int [ ] [ ] info = new int [ n + 1 ] [ m + 1 ] ;
  int prey = y ;
  for ( int i = x ;
  i >= 1 ;
  i -- ) {
    info [ i ] [ prey ] = 1 ;
    System . out . println ( i + " " + prey ) ;
    for ( int j = 1 ;
    j <= m ;
    j ++ ) {
      if ( info [ i ] [ j ] != 1 ) {
        prey = j ;
        System . out . println ( i + " " + j ) ;
      }
    }
  }
  for ( int i = x + 1 ;
  i <= n ;
  i ++ ) {
    info [ i ] [ prey ] = 1 ;
    System . out . println ( i + " " + prey ) ;
    for ( int j = 1 ;
    j <= m ;
    j ++ ) {
      if ( info [ i ] [ j ] != 1 ) {
        prey = j ;
        System . out . println ( i + " " + j ) ;
      }
    }
  }
}

public static void main ( String [ ] args ) throws IOException { BufferedReader reader = new BufferedReader ( new InputStreamReader ( System . in ) ) ; String [ ] tmp = reader . readLine ( ) . split ( " ▁ " ) ; int n = Integer . valueOf ( tmp [ 0 ] ) ; int m = Integer . valueOf ( tmp [ 1 ] ) ; int x = Integer . valueOf ( tmp [ 2 ] ) ; int y = Integer . valueOf ( tmp [ 3 ] ) ; int [ ] [ ] info = new int [ n + 1 ] [ m + 1 ] ; int prey = y ; for ( int i = x ; i >= 1 ; i -- ) { info [ i ] [ prey ] = 1 ; System . out . println ( i + " ▁ " + prey ) ; for ( int j = 1 ; j <= m ; j ++ ) { if ( info [ i ] [ j ] != 1 ) { prey = j ; System . out . println ( i + " ▁ " + j ) ; } } } for ( int i = x + 1 ; i <= n ; i ++ ) { info [ i ] [ prey ] = 1 ; System . out . println ( i + " ▁ " + prey ) ; for ( int j = 1 ; j <= m ; j ++ ) { if ( info [ i ] [ j ] != 1 ) { prey = j ; System . out . println ( i + " ▁ " + j ) ; } } } }
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