public static void main ( String [ ] args ) {
  Scanner in = new Scanner ( System . in ) ;
  PrintWriter out = new PrintWriter ( System . out , true ) ;
  long [ ] [ ] comb = new long [ MAXN ] [ MAXN ] ;
  comb [ 0 ] [ 0 ] = 1 ;
  for ( int i = 1 ;
  i < MAXN ;
  i ++ ) {
    comb [ i ] [ 0 ] = 1 ;
    for ( int j = 1 ;
    j <= i ;
    j ++ ) {
      comb [ i ] [ j ] = ( comb [ i - 1 ] [ j ] + comb [ i - 1 ] [ j - 1 ] ) % mod ;
    }
  }
  int K = in . nextInt ( ) ;
  int [ ] color = new int [ K ] ;
  for ( int i = 0 ;
  i < K ;
  i ++ ) color [ i ] = in . nextInt ( ) ;
  long res = 1 ;
  int total = 0 ;
  for ( int i = 0 ;
  i < K ;
  i ++ ) {
    res = ( res * comb [ total + color [ i ] - 1 ] [ color [ i ] - 1 ] ) % mod ;
    total += color [ i ] ;
  }
  out . println ( res ) ;
  out . close ( ) ;
  System . exit ( 0 ) ;
}

public static void main ( String [ ] args ) { Scanner in = new Scanner ( System . in ) ; PrintWriter out = new PrintWriter ( System . out , true ) ; long [ ] [ ] comb = new long [ MAXN ] [ MAXN ] ; comb [ 0 ] [ 0 ] = 1 ; for ( int i = 1 ; i < MAXN ; i ++ ) { comb [ i ] [ 0 ] = 1 ; for ( int j = 1 ; j <= i ; j ++ ) { comb [ i ] [ j ] = ( comb [ i - 1 ] [ j ] + comb [ i - 1 ] [ j - 1 ] ) % mod ; } } int K = in . nextInt ( ) ; int [ ] color = new int [ K ] ; for ( int i = 0 ; i < K ; i ++ ) color [ i ] = in . nextInt ( ) ; long res = 1 ; int total = 0 ; for ( int i = 0 ; i < K ; i ++ ) { res = ( res * comb [ total + color [ i ] - 1 ] [ color [ i ] - 1 ] ) % mod ; total += color [ i ] ; } out . println ( res ) ; out . close ( ) ; System . exit ( 0 ) ; }
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