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:
| name | pos. | caps | goals | club |
| --- | --- | --- | --- | --- |
| Olle Åhlund | MF | 1 | 0 | Degerfors IF |
| Sune "Mona-Lisa" Andersson | MF | 5 | 0 | AIK Solna |
| Henry "Garvis" Carlsson | FW | 2 | 0 | AIK Solna |
| Rune "Killing" Emanuelsson | MF | 2 | 0 | IFK Göteborg |
| Thure Grahn | DF | 1 | 0 | IS Halmia Halmstad |
| Gunnar "Il Professore" Gren | FW | 5 | 5 | IFK Göteborg |
| Sven "Jack" Jacobsson | MF | 1 | 0 | GAIS Göteborg |
| Egon "Hemliga" Jönsson | FW | 1 | 0 | Malmö FF |
| Börje Leander | MF | 1 | 0 | AIK Solna |
| Nils "Lidas"/"Greven" Liedholm | FW | 6 | 5 | IFK Norrköping |
| Torsten "Lindy" Lindberg | GK | 5 | 0 | IFK Norrköping |
| Lennart Lindskog | FW | 1 | 0 | Degerfors IF |
| Malte "Svarta Blixten" Mårtensson | FW | 2 | 0 | Hälsingborgs IF |
| Erik Nilsson | DF | 4 | 0 | Malmö FF |
| Harry Nilsson | DF | 2 | 0 | AIK Solna |
| Ove Nilsson | GK | 1 | 0 | Djurgårdens IF Stockholm |
| Stellan Nilsson | FW | 4 | 0 | Malmö FF |
| Bertil Nordahl | MF | 4 | 0 | Degerfors IF |
| Gunnar Nordahl | FW | 6 | 8 | IFK Norrköping |
| Knut Nordahl | DF | 5 | 0 | IFK Norrköping |
| Stig Nyström | FW | 1 | 1 | Djurgårdens IF Stockholm |
| Kjell Rosén | MF/FW | 4 | 0 | Malmö FF |
| Birger "Bian" Rosengren | MF | 1 | 0 | IFK Norrköping |
| Rolf Svensson | FW | 1 | 0 | Hälsingborgs IF |
| Börje Tapper | FW | 1 | 1 | Malmö FF |
Question:
how many defensive (df) players are there on the national team?
Answer:
4