>items=["map","compass","water","sandwich","glucose", ...
>  "tin","banana","apple","cheese","beer","suntan creame", ...
>  "camera","t-shirt","trousers","umbrella","waterproof trousers", ...
>  "waterproof overclothes","note-case","sunglasses", ...
>  "towel","socks","book"];
>ws = [9,13,153,50,15,68,27,39,23,52,11, ...
>  32,24,48,73,42,43,22,7,18,4,30];
>vs = [150,35,200,160,60,45,60,40,30,10,70, ...
>  30,15,10,40,70,75,80,20,12,50,10];
>A=ws_id(cols(ws));
>c=vs;
>b=[400]_ones(cols(vs),1);
>sol = intsimplex(A,b,c,eq=-1,>max,>check);
>items[nonzeros(sol)]
 map
 compass
 water
 sandwich
 glucose
 banana
 suntan creame
 waterproof trousers
 waterproof overclothes
 note-case
 sunglasses
 socks