user: Question: How many entries for prothrombin time are there where platelet count is "Decreased or unaffected"?
Columns: ['Condition', 'Prothrombin time', 'Partial thromboplastin time', 'Bleeding time', 'Platelet count']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Vitamin K deficiency or warfarin', 'Prolonged', 'Normal or mildly prolonged', 'Unaffected', 'Unaffected']
SQL:

assistant: SELECT COUNT("Prothrombin time") FROM "Table" WHERE "Platelet count" = 'Decreased or unaffected';