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:
| Rank | Nation | Gold | Silver | Bronze | Total |
| --- | --- | --- | --- | --- | --- |
| 1 | Nigeria | 13 | 5 | 6 | 24 |
| 2 | South Africa | 11 | 11 | 8 | 30 |
| 3 | Ethiopia | 6 | 3 | 2 | 11 |
| 4 | Kenya | 5 | 4 | 8 | 17 |
| 5 | Tunisia | 2 | 2 | 1 | 5 |
| 6 | Senegal | 2 | 1 | 3 | 6 |
| 7 | Ghana | 2 | 0 | 4 | 6 |
| 8 | Cameroon | 1 | 4 | 1 | 6 |
| 9 | Egypt | 1 | 1 | 2 | 4 |
| 10 | Mauritius | 1 | 0 | 1 | 2 |
| 11 | Mozambique | 1 | 0 | 0 | 1 |
| 12 | Algeria | 0 | 8 | 1 | 9 |
| 13 | Madagascar | 0 | 2 | 1 | 3 |
| 14 | Zimbabwe | 0 | 1 | 1 | 2 |
| 15 | Tanzania | 0 | 1 | 0 | 1 |
| 15 | Togo | 0 | 1 | 0 | 1 |
| 15 | Burkina Faso | 0 | 1 | 0 | 1 |
| 18 | Central African Republic | 0 | 0 | 1 | 1 |
| 18 | Uganda | 0 | 0 | 1 | 1 |
| 18 | Namibia | 0 | 0 | 1 | 1 |
| 18 | Ivory Coast | 0 | 0 | 1 | 1 |
Question:
what is the difference of silver medals between south africa and kenya?
Answer:
7