Quantos anos anteriores a escola secundária Maebashi Ikuei teve um número total de 1 participação?
CREATE TABLE table_2518850_4 (year_of_previous_participation VARCHAR, total_number_of_participation VARCHAR, high_school_name VARCHAR)
SELECT COUNT(year_of_previous_participation) FROM table_2518850_4 WHERE total_number_of_participation = 1 AND high_school_name = "Maebashi Ikuei"