Stuck at creating formula count formula

[xaabz]

I want to create a formula that will count the records if ST1 matches the records with ST2 on the same Number. For example, the Number 2 St1 value is LAS, and ST2 value is LAS similarly LAS value is matching in numbers ST1 and ST2 both. Please help me define this formula. Attached is the Excel for sample

[geraldo]

@xaabz 

An workflow example

[xaabz]

I think it's incorrect because ideally it only should populate 2 records that were highlighted in the Excel. I also create a new tab for you to see those highlighted records should not populate based on the given data I provided

[geraldo]

@xaabz 

Yes, I understood. But number 3 has 1 LAS in ST1 and 2 ST2. You need to improve your rule to not form Cartesian. In the rule that does not correspond or that there is only one formula is valid. But for number 3 and others that may have more than 1 correspondent in St2 what is the rule?

[xaabz]

Here is the updated sample data. I want to pull up that matches the records if the Flag_ST is the same as Dep_ST and Dep_ST should be the same like Arr_ST on the same Date, Days, and  Last (Sequence in Days) columns.

I highlighted some records for reference for better clarity

[geraldo]

@xaabz 

This sample data is now more clear. See this example are all columns in one row only if this needs adjustments to what you want as the final result