Not Sure How to Resolve "Contextstack overflow" error

I have some data that looks like the following:

UniqueID MonthYear Count2 CCount
402ABC   OCT2018   5      1               
402ABC   NOV2018   5      2               
402ABC   DEC2018   5      3               
402ABC   JAN2019   5      4              
402ABC   FEB2019   5      5               
495DEF   FEB2019  10      1      
495DEF   MAR2019  10      2      
495DEF   APR2019  10      3      
495DEF   MAY2019  10      4     
495DEF   JUN2019  10      5     
495DEF   AUG2019  10      6     
495DEF   SEP2019  10      7     
495DEF   DEC2019  10      8    
495DEF   JAN2020  10      9    
495DEF   FEB2020  10     10    

What I want is to be able to create a new column titled "Corrected" that finds the last instance of a UniqueID. Ideally, the new data would look like the following:

UniqueID MonthYear Count2 CCount Corrected
402ABC   OCT2018   5      1      0         
402ABC   NOV2018   5      2      0          
402ABC   DEC2018   5      3      0         
402ABC   JAN2019   5      4      0        
402ABC   FEB2019   5      5      1         
495DEF   FEB2019  10      1      0
495DEF   MAR2019  10      2      0
495DEF   APR2019  10      3      0
495DEF   MAY2019  10      4      0
495DEF   JUN2019  10      5      0
495DEF   AUG2019  10      6      0
495DEF   SEP2019  10      7      0
495DEF   DEC2019  10      8      0
495DEF   JAN2020  10      9      0
495DEF   FEB2020  10     10      1

I had a series of nested ifelse functions used to create the "Corrected" column in my data frame. The nested chunk looked like the following:

smd$Corrected=ifelse(smd$MonthYear=="OCT2018" & smd$Count2==1, 1,ifelse(
                     smd$MonthYear=="OCT2018" & smd$Count2 >1, 0,ifelse(
    
                     smd$MonthYear=="NOV2018" & smd$Count2==1, 1,ifelse(
                     smd$MonthYear=="NOV2018" & smd$Count2==smd$CCount, 1,ifelse(
                     smd$MonthYear=="NOV2018" & smd$Count2!=smd$CCount, 0,ifelse(
          
                     smd$MonthYear=="DEC2018" & smd$Count2==1, 1,ifelse(
                     smd$MonthYear=="DEC2018" & smd$Count2==smd$CCount, 1,ifelse(
                     smd$MonthYear=="DEC2018" & smd$Count2!=smd$CCount, 0,ifelse(
………………………


                     smd$MonthYear=="MAY2020" & smd$Count2==1, 1,ifelse(
                     smd$MonthYear=="MAY2020" & smd$Count2==smd$CCount, 1,ifelse(
                     smd$MonthYear=="MAY2020" & smd$Count2!=smd$CCount, 0,0
                                                                
             )))))))))))))))))))))))))))))))))))))))))))))))))))))

I understand this was not the most elegant solution, but it worked for my purposes. This is just one part of a larger analysis I was running. The analysis was updated once every month and I added a new chunk to this code each time I updated it. Today, when I attempted to update the code, I got the following error:

Error: contextstack overflow at line 66

Doing a little bit of research, I learned that this error pops up when you use too many nested ifelse statements. Other questions on StackOverflow suggested I use either sapply or mapply to rewrite this code. I tried a couple of apply functions here to rewrite my code, but nothing seemed to work quite right.

Can anyone help suggesting how I would rewrite my code to not use all the nested ifelse functions? Any help would be appreciated!

Thank you!