import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner sc = new Scanner(System.in); int N = sc.nextInt(); sc.close(); long[] dp = new long[N + 1]; dp[1] = 1; dp[2] = 1; for(int i = 1; i < N; i++) { if(dp[i] != 0) { if(i + 1 <= N) { dp[i + 1] += dp[i]; } if(i + 2 <= N) { dp[i + 2] += dp[i]; } } } System.out.println(dp[N]); } }