user: Question: What is the length of retirement for president Sharma, Shankar Shankar Dayal Sharma?
Columns: ['President', 'Date of birth', 'Date of inauguration', 'Age at inauguration', 'End of term', 'Length of retirement', 'Date of death', 'Lifespan']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Prasad, Rajendra Rajendra Prasad', '1884-12-03 3 December 1884', '26January1950', '65-054 65years, 54days', '13May1962', '0,291 days', '1963-02-28 28 February 1963', 'days (78years, 87days)']
SQL:

assistant: SELECT "Length of retirement" FROM "Table" WHERE "President" = 'Sharma, Shankar Shankar Dayal Sharma';