import java.math.*;
import java.io.*;
public class FibonacciTest
{

	
	private static BigInteger[] answers;
	private static BufferedReader stdin = new BufferedReader( new InputStreamReader( System.in ) );
	private static BigInteger one;
	private static BigInteger zero;


        public static int fibonacci(int n)
        {
                if((n == 1) || (n == 2))
                        return 1;
                else
                        return fibonacci(n-1) + fibonacci(n-2);
        }

	public static BigInteger fastFibonacci(int n)
	{
		if((n == 1) || (n == 2))
                        return answers[0];

                if(answers[n-1].compareTo(zero) != 0)
                        return answers[n-1];

		if(answers[n-2].compareTo(zero) == 0)
                	answers[n-2] = fastFibonacci(n-1);

		if(answers[n-3].compareTo(zero) == 0)
                	answers[n-3] = fastFibonacci(n-2);

                return answers[n-2].add(answers[n-3]);
	}

        public static void main(String[] args)
        {

                int n;
                // Prompt the user
                System.out.println("Type a positive integer." );
                try{

                        // Read a line of text from the user.
                        String input = stdin.readLine();

                        // converts a String into an int value
                        n = Integer.parseInt( input );
			
			zero = new BigInteger("0");
			one = new BigInteger("1");

			// Initializing answers
			answers = new BigInteger[n];
			answers[0] = new BigInteger("1");
			answers[1] = new BigInteger("1");
			for(int i = 2; i < n; i++)
				answers[i] = new BigInteger("0");

                        System.out.println("The "+n+"th Fibonacci number is "+fastFibonacci(n));
                        //System.out.println("The "+n+"th Fibonacci number is "+fibonacci(n));
                }
                catch(java.io.IOException e)
                {
                        System.out.println(e);
                }

		

	} // end of main
	
} // end of class