p:printf;r:?read;s:"~v,'0b
";f(n,r,x):=if r=0 then p(?t,s,a,x)elseif n=r then p(?t,s,a,x+2^r-1)else(f(n-1,r,x),f(n-1,r-1,x+2^(n-1)));f(a:r(),r(),0);