import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.PrintWriter; import java.util.ArrayList; import java.util.StringTokenizer; public class Main { static BufferedReader in; static PrintWriter out; static StringTokenizer tok; void solve() throws IOException { int n = ni(); int[][] dp = new int[3][n + 1]; int MOD = (int) 1e9 + 7; dp[0][1] = 1; for (int i = 2; i <= n; i++) { dp[0][i] = dp[2][i - 1]; dp[1][i] = dp[0][i - 1]; dp[2][i] = (dp[0][i - 1] + dp[1][i - 1]) % MOD; } int ans = 0; for (int i = 0; i < 3; i++) { ans = (ans + dp[i][n]) % MOD; } out.println(ans); } String ns() throws IOException { while (!tok.hasMoreTokens()) { tok = new StringTokenizer(in.readLine(), " "); } return tok.nextToken(); } int ni() throws IOException { return Integer.parseInt(ns()); } long nl() throws IOException { return Long.parseLong(ns()); } double nd() throws IOException { return Double.parseDouble(ns()); } String[] nsa(int n) throws IOException { String[] res = new String[n]; for (int i = 0; i < n; i++) { res[i] = ns(); } return res; } int[] nia(int n) throws IOException { int[] res = new int[n]; for (int i = 0; i < n; i++) { res[i] = ni(); } return res; } long[] nla(int n) throws IOException { long[] res = new long[n]; for (int i = 0; i < n; i++) { res[i] = nl(); } return res; } public static void main(String[] args) throws IOException { in = new BufferedReader(new InputStreamReader(System.in)); out = new PrintWriter(System.out); tok = new StringTokenizer(""); Main main = new Main(); main.solve(); out.close(); } }