There is now row at position 4 error get when try to remove

Question

problem

 

There is now row at position 4 error get when try to remove unitcode exist on another datatble  

I have two data tables

dtwrongvaluesFinal

dtcheckrepeated

dtwrongvaluesFinal data as Following :

UnitCode    CurrentReading
122            50
123            12
7678           23
1290           17

dtcheckrepeated data show only data repeating on excel sheet as following

UnitCode CurrentReading
 122           50
122             12
7678           23
7678           17

Actually i need to remove UnitCode that repeated in dtcheckrepeated from datatable dtwrongvaluesFinal

so that i write code below but problem it give me exception error there is no row at position 4 but problem i dont know

How to handle it

my code as below

if (dtwrongvaluesFinal.Rows.Count > 0)
{
    for (int j = 0; j <= dtwrongvaluesFinal.Rows.Count-1; j++)
    {
        if (dtcheckrepeated.Rows.Count > 0)
        {
            for (int m = 0; m <= dtcheckrepeated.Rows.Count-1; m++)
            {
                if (j <= dtcheckrepeated.Rows.Count - 1)
                {
 UnitCodeWrongchk = Utilities.ObjectConverter.ConvertToString(dtcheckrepeated.Rows[j]["UnitCode"]);
UnitCodeWrongchkwrong = Utilities.ObjectConverter.ConvertToString(dtcheckrepeated.Rows[m]["UnitCode"]);
                if (UnitCodeWrongchkwrong == UnitCodeWrongchk)
                {
                    dtwrongvaluesFinal.Rows.RemoveAt(m);
                }
            }
        }
    }
    dtwrongvaluesFinal.AcceptChanges();
  }
 }

The error show on line

UnitCodeWrongchk = Utilities.ObjectConverter.ConvertToString(dtcheckrepeated.Rows[j]["UnitCode"]);

 

dtwrongvaluesFinal.Rows.Count is 20 and

dtcheckrepeated.Rows.Count is 4

 

So that How to handle this error please ?