155802

All the numbers must add up to fifteen. The answer must also have a 1 because there is no other way to make 1 and you must make all numbers from 1-15.
So 1+0=1. Then to make 2 you can either have 1+1 or 2+0 but you only have four bags so for minimum numbers use the two. This means you can also make the 3 by adding 2+1. Then you need to make the four so you can add 4+0 or add more 2s or other numbers but the four is quickest. Then you can add 4+1 to get 5 then 4+2 to get 7. Then you need to get eight but only have one number left. So you must do 8+0 to get the 8 and can then do 8+1=9, 8+2=10, 8+2+1=11, 8+4=12, 8+4+1=13, 8+4+2=14, 8+4+2+1=15. Which means you can get all the numbers you need.