import java.util.Scanner;

public class Test {
	public static Scanner sc = new Scanner(System.in);

	public static void main(String[] args) {
		int n = sc.nextInt();
		if(n < 3){
			System.out.println(n);
		}
		long t00 = 1, t01 = 1, t10 = 0, tmp, e = 1000000007;
		for(int i = 3; i <= n; i++){
			tmp = t00 + t10;
			t00 = t10;
			t10 = t01;
			t01 = tmp % e;
		}
		System.out.println((t00+t01+t10)%e);
	}
}