Hello everyone, I have a problem with binpacking, please help

Given N packages, each type belongs to only 2 types: 1 liter and 2 liters. There are containers, each containing a maximum of 200 liters. These N packages are packed in the correct order, and there will be a maximum of 2 boxes opened at the same time. When one box cannot hold any more packages, it will be closed and a new box will be opened. Find the minimum number of boxes to hold N packages.

I am currently researching some problems from the PTZ camp, can someone give me the solution of the problems there? Any year is fine