import java.math.BigInteger;
public class BigFastFib {
    static BigInteger[] done = new BigInteger[5001];
    public static BigInteger f(int n) {
	if (n <= 1) return BigInteger.ONE;
	if (done[n] == null) done[n] = f(n-1).add(f(n-2));
	return done[n];
    }
    public static void main(String[] args) {
	int n = new Integer(args[0]);
	System.out.println("The " + n + "th fibonacci is " + f(n));
    }
}