public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int tc = sc . nextInt ( ) ;
  while ( tc -- > 0 ) {
    long ha = sc . nextInt ( ) ;
    long hb = sc . nextInt ( ) ;
    int n = sc . nextInt ( ) ;
    int a [ ] = new int [ n ] ;
    int b [ ] = new int [ n ] ;
    for ( int i = 0 ;
    i < n ;
    i ++ ) {
      a [ i ] = sc . nextInt ( ) ;
    }
    for ( int i = 0 ;
    i < n ;
    i ++ ) {
      b [ i ] = sc . nextInt ( ) ;
    }
    long x , max = 0 ;
    for ( int i = 0 ;
    i < n ;
    i ++ ) {
      x = ( b [ i ] + ha - 1 ) / ha ;
      hb -= x * a [ i ] ;
      max = Math . max ( max , a [ i ] ) ;
    }
    if ( hb + max > 0 ) System . out . println ( "YES" ) ;
    else System . out . println ( "NO" ) ;
  }
  sc . close ( ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int tc = sc . nextInt ( ) ; while ( tc -- > 0 ) { long ha = sc . nextInt ( ) ; long hb = sc . nextInt ( ) ; int n = sc . nextInt ( ) ; int a [ ] = new int [ n ] ; int b [ ] = new int [ n ] ; for ( int i = 0 ; i < n ; i ++ ) { a [ i ] = sc . nextInt ( ) ; } for ( int i = 0 ; i < n ; i ++ ) { b [ i ] = sc . nextInt ( ) ; } long x , max = 0 ; for ( int i = 0 ; i < n ; i ++ ) { x = ( b [ i ] + ha - 1 ) / ha ; hb -= x * a [ i ] ; max = Math . max ( max , a [ i ] ) ; } if ( hb + max > 0 ) System . out . println ( " YES " ) ; else System . out . println ( " NO " ) ; } sc . close ( ) ; }
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