items:=T( // item: (name,weight,value,#)
   T("apple",      39, 40,3),T("banana",   27,60,3),
   T("beer",       52, 10,3),T("book",     30,10,2),T("camera",      32, 30,1),
   T("cheese",     23, 30,1),T("compass",  13,35,1),T("glucose",     15, 60,2),
   T("map",         9,150,1),T("note-case",22,80,1),T("sandwich",    50, 60,2),
   T("socks",       4, 50,1),T("sunglasses",7,20,1),T("suntan cream",11, 70,1),
   T("t-shirt",    24, 15,2),T("tin",      68,45,3),T("towel",       18, 12,2),
   T("trousers",   48, 10,2),T("umbrella", 73,40,1),T("water",      153,200,2),
   T("overclothes",43, 75,1),T("waterproof trousers",42,70,1) );
weight:='wrap(knapsack){ // knapsack is (cost, (nm,#,nm,#...))
   knapsack[1].pump(List,Void.Read, // read nm,#, first read is implicit
      'wrap(nm,n){ items[items.filter1n(fcn(it,nm){ it[0]==nm },nm)][1]*n })
      .sum(0)
};