Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Departure | Going to | Calling at | Arrival | Operator |
| --- | --- | --- | --- | --- |
| 06.40 | Stamford East | Ryhall & Belmesthorpe, Stamford East | 06.50 | GNR |
| 08.10 | Stamford East | Ryhall & Belmesthorpe, Stamford East | 08.20 | GNR |
| 08.30 | Bourne | Braceborough Spa, Thurlby, Bourne | 08.50 | GNR |
| 08.56 | Stamford East | Ryhall & Belmesthorpe, Stamford East | 09.06 | GNR |
| 09.52 | Grantham | Little Bytham, Corby, Great Ponton, Grantham | 10.35 | GNR |
| 10.05 | Stamford East | Ryhall & Belmesthorpe, Stamford East | 10.15 | GNR |
| 10.05 | Bourne | Braceborough Spa, Thurlby, Bourne | 10.25 | GNR |
| 11.07 | Grantham | Little Bytham, Corby, Great Ponton, Grantham | 11.40 | GNR |
| 11.27 | Peterborough North | Tallington, Peterborough North | 11.46 | GNR |
| 11.30 | Bourne | Braceborough Spa, Thurlby, Bourne | 11.45 | GNR |
| 11.35 | Stamford East | Ryhall & Belmesthorpe, Stamford East | 11.45 | GNR |
| 13.25 | Peterborough North | Peterborough North | 13.41 | GNR |
| 13.30 | Stamford East | Ryhall & Belmesthorpe, Stamford East | 13.39 | GNR |
| 14.10 | Stamford East | Ryhall & Belmesthorpe, Stamford East | 14.20 | GNR |
| 14.22 | Bourne | Braceborough Spa, Thurlby, Bourne | 14.37 | GNR |
| 15.50 | Grantham | Grantham | 16.11 | GNR |
| 16.05 | Stamford East | Ryhall & Belmesthorpe, Stamford East | 16.15 | GNR |
| 16.05 | Bourne | Braceborough Spa, Thurlby, Bourne | 16.25 | GNR |
| 17.17 | Peterborough North | Tallington, Peterborough North | 17.36 | GNR |
| 17.25 | Stamford East | Ryhall & Belmesthorpe, Stamford East | 17.35 | GNR |
| 17.25 | Bourne | Braceborough Spa, Thurlby, Bourne | 17.40 | GNR |
| 18.48 | Grantham | Little Bytham, Grantham | 19.13 | GNR |
| 19.09 | Stamford East | Ryhall & Belmesthorpe, Stamford East | 19.19 | GNR |
| 19.12 | Bourne | Braceborough Spa, Thurlby, Bourne | 19.26 | GNR |
Question:
what is the operator of trains arriving at 13.39 
Answer:
GNR