Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_21 (erp_w INTEGER, call_sign VARCHAR)
### Question:
When the call sign is wpib, what is lowest ERP W?
### Answer:
SELECT MIN(erp_w) FROM table_name_21 WHERE call_sign = "wpib"