(define n (read))

(define (f a b c n)
	(if (= n 0)
		(remainder (+ a b c) 1000000007)
		(f (remainder (+ b c) 1000000007) a b (- n 1))))

(define r (number->string (f 0 1 0 (- n 1))))

(print (car (string-split r ".")))