user: Question: who ended runner-up to Sankar Adhi?
Columns: ['Constituency', 'Winner', 'Party', 'Margin', 'Runner-up a', 'Party a']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['1. Thiruvallur (SC)', 'P. Venugopal', 'ADMK', 31673.0, 'S. Gayathri', 'DMK']
SQL:

assistant: SELECT "Runner-up a" FROM "Table" WHERE "Winner" = 'Sankar Adhi';