SELECT T3.service_id, T4.service_type_code FROM participants AS T1 JOIN participants_in_events AS T2 ON T1.participant_id = T2.participant_id JOIN events AS T3 ON T2.event_id = T3.event_id JOIN services AS T4 ON T3.service_id = T4.service_id GROUP BY T3.service_id ORDER BY COUNT(*) LIMIT 1
Which service id and type has the least number of participants?
CREATE TABLE participants (
    participant_id number,
    participant_type_code text,
    participant_details text
)

CREATE TABLE events (
    event_id number,
    service_id number,
    event_details text
)

CREATE TABLE participants_in_events (
    event_id number,
    participant_id number
)

CREATE TABLE services (
    service_id number,
    service_type_code text
)