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:
| High School | Join\nYear | From | Left | league left to |
| --- | --- | --- | --- | --- |
| Ainsworth | 1954 |  | 1961 | Big Nine Conference |
| Atherton | 1960 |  | 1976 | Mid-Eastern Eight Conference |
| Beecher | 1950 |  | 1960 | Big Nine Conference |
| Bendle | 1950 |  | 1975 | Mid-Eastern Eight Conference |
| Bentley | 1960 |  | 1978 | Genesee Eight |
| Brandon | 1977 |  | 1978 | Five County 5 League |
| Clio | 1950 |  | 1960 | Big Nine Conference |
| Davison | 1950 |  | 1960 | Big Nine Conference |
| Durand | 1964 |  | 1978 | Flint Metro League |
| Fenton | 1940 |  | 1968 | Flint Metro League |
| Flushing | 1950 |  | 1960 | Big Nine Conference |
| Grand Blanc | 1950 |  | 1960 | Big Nine Conference |
| Hartland | 1976 |  | 1978 | Five County 5 |
| Kearsley | 1950 |  | 1960 | Big Nine Conference |
| Lake Fenton | 1976 |  | 1978 | Genesee Eight |
| LakeVille | 1956\n2nd: 1964 |  | 1962\n2nd: 1976 | Independent\n2nd: Flint Metro League |
| Linden | 1974 |  | 1978 | Genesee Eight |
| Mt. Morris | 1950 |  | 1960 | Big Nine Conference |
| Swartz Creek | 1960 | County C League | 1968 | Flint Metro League |
Question:
how many schools left the genesee county b league before ainsworth?
Answer:
7