public static void main ( String [ ] args ) {
  Scanner in = new Scanner ( System . in ) ;
  int T = in . nextInt ( ) ;
  for ( int t = 0 ;
  t < T ;
  t ++ ) {
    int AH = in . nextInt ( ) ;
    long DH = in . nextInt ( ) ;
    int N = in . nextInt ( ) ;
    int [ ] A = new int [ N ] ;
    int [ ] D = new int [ N ] ;
    for ( int n = 0 ;
    n < N ;
    n ++ ) {
      A [ n ] = in . nextInt ( ) ;
    }
    for ( int n = 0 ;
    n < N ;
    n ++ ) {
      D [ n ] = in . nextInt ( ) ;
    }
    int max = 0 ;
    for ( int n = 0 ;
    n < N ;
    n ++ ) {
      long attacks = ( D [ n ] + AH - 1 ) / AH ;
      DH -= attacks * A [ n ] ;
      max = Math . max ( max , A [ n ] ) ;
    }
    DH += max ;
    System . out . println ( DH > 0 ? "YES" : "NO" ) ;
  }
}

public static void main ( String [ ] args ) { Scanner in = new Scanner ( System . in ) ; int T = in . nextInt ( ) ; for ( int t = 0 ; t < T ; t ++ ) { int AH = in . nextInt ( ) ; long DH = in . nextInt ( ) ; int N = in . nextInt ( ) ; int [ ] A = new int [ N ] ; int [ ] D = new int [ N ] ; for ( int n = 0 ; n < N ; n ++ ) { A [ n ] = in . nextInt ( ) ; } for ( int n = 0 ; n < N ; n ++ ) { D [ n ] = in . nextInt ( ) ; } int max = 0 ; for ( int n = 0 ; n < N ; n ++ ) { long attacks = ( D [ n ] + AH - 1 ) / AH ; DH -= attacks * A [ n ] ; max = Math . max ( max , A [ n ] ) ; } DH += max ; System . out . println ( DH > 0 ? " YES " : " NO " ) ; } }
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