new: 4
size 0
append 2.5 1
append 3.1 1
size 2
append 1.7 1
sum 7.3
assign 
   append 5.4 1
   size 4
   sum 12.7
   delete
exit
size 3
sum 7.3
append 1.2 1
sum 8.5
append 8.9 0
cout
delete
summary
exit