import java.io.BufferedReader; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.Arrays; import java.util.Comparator; import java.util.List; import java.util.TreeSet; public class Main { public static int w; public static int k; public static int n; // public static int[][] dp; public static int[] a; public static int[] b; public static List list = new ArrayList(); public static TreeSet set = new TreeSet(); // public static PriorityQueue pq = new PriorityQueue(); public static void main(String[] args) throws NumberFormatException, IOException{ ContestScanner in = new ContestScanner(); n = in.nextInt(); long[] dp = new long[n+1]; dp[0] = 1; dp[1] = 1; for(int i=2; i<=n; i++){ dp[i] = dp[i-1] + dp[i-2]; } System.out.println(dp[n]); } } class Node{ int id; List edge = new ArrayList(); public Node(int id){ this.id = id; } public void createEdge(Node node){ edge.add(node); } } class MyMath{ public static long fact(long n){ long res = 1; while(n > 0){ res *= n--; } return res; } public static long[][] pascalT(int n){ long[][] tri = new long[n][]; for(int i=0; i{ public int compare(Integer arg0, Integer arg1) { return arg0 - arg1; } } // //class MyCompB implements Comparator{ // public int compare(int[] arg0, int[] arg1) { // return arg0[1] - arg1[1]; // } //} class ContestScanner{ private BufferedReader reader; private String[] line; private int idx; public ContestScanner() throws FileNotFoundException{ reader = new BufferedReader(new InputStreamReader(System.in)); } public String nextToken() throws IOException{ if(line == null || line.length <= idx){ line = reader.readLine().trim().split(" "); idx = 0; } return line[idx++]; } public long nextLong() throws IOException, NumberFormatException{ return Long.parseLong(nextToken()); } public int nextInt() throws NumberFormatException, IOException{ return (int)nextLong(); } public double nextDouble() throws NumberFormatException, IOException{ return Double.parseDouble(nextToken()); } }