SCHEMA:
CREATE TABLE table_name_36 (stage INTEGER, finish VARCHAR, year VARCHAR, leader_at_the_summit VARCHAR)
USER:
What is the highest stage number for a year later than 1948, leader at the summit was group, and finish was Bagnères-De-Bigorre?

QUERY:
SELECT MAX(stage) FROM table_name_36 WHERE year > 1948 AND leader_at_the_summit = "group" AND finish = "bagnères-de-bigorre"