List all the public institutes from the state with the least number of graduate cohort in 2013.
public refers to control = 'Public'; institutes refers to chronname; least number of graduate cohort refers to MIN(grad_cohort); in 2013 refers to year = 2013;
SELECT T1.chronname FROM institution_details AS T1 INNER JOIN state_sector_grads AS T2 ON T1.state = T2.state WHERE T2.year = 2013 AND T1.control = 'Public' ORDER BY T2.grad_cohort LIMIT 1