function add(a,key,val, i) { 
	i       = ++a[0]; 
	a[i]    = key; 
	a[-1*i] = val 
	a["+"] += val
}
function sample(a,  sum,r,max,i) {
	r   = rand();
	max = a[0];
	sum = a["+"];
	for(i=1; i<=max; i++) 
		if (a[-1*i]/sum > r)
			return i
}
function sampleDemo(  a,n) {
	n=20;
	add(a,"mon",2)	
	add(a,"tue",4)	
	add(a,"wed",8)	
	add(a,"thu",1)	
	add(a,"fri",1)	
	saya("a1",a);
	while(n--) print a[sample(a)]
	saya("a2",a);
}