Formula to calculate number of employees per new location added

Hello, I need help with a formula.

Year Locations Added

2023 1
2024 1
2025 2
2026 2
2027 3
2028 6
2029 7

I want to add 1 new employee every 3 new locations added.
For Example: In 2023, 1 new location is added therefore no new employee in 2023. In 2024, 1 new location is added therefore the sum is now 2 hence again no new employee should be added in 2024. But in 2025, 2 new locations are added. If you take the cumulative sum of new locations, it is now 4. So one new employee should be added. (Sum = 4 : 1 New employee per 3 locations) and the remaining 1 location from 4 should be carried forward to the next year and sum should start again until it reaches 3.

Try this in C2 and copied down.

=INT((SUM($B$2:B2)-3*SUM($C$1:C1))/3)

Try, C2=QUOTIENT(SUM(B$2:B2),3), copy down.