CREATE TABLE table_2518850_4 (year_of_previous_participation VARCHAR(255), total_number_of_participation VARCHAR(255), high_school_name VARCHAR(255))
How many previous years did Maebashi Ikuei high school have a total number of 1 participation?
    
SQL: SELECT COUNT(year_of_previous_participation) FROM table_2518850_4 WHERE total_number_of_participation = 1 AND high_school_name = "Maebashi Ikuei"