Can you clarify some details? Imagine we have this situation:

10   15
20   5
30   35
40
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Now, R2 gives 10 and R1 gives 50, 25. Should I put 50 into 4th track because of 40, or is 40 already forgotten?

What is the expected output of the program? Should it just return the new status based on R2 and R1 for each step, or should it build a structure representing the whole process?