UVA - 10862 - Connect the Cable Wires

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;

public class Main {

    public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        StringBuffer sb = new StringBuffer("");
        String m = "";
        BigInteger fib[] = new BigInteger[4001];
        fib[0] = BigInteger.ONE;
        fib[1] = BigInteger.ONE;
        for (int i = 2; i < 4001; i++) {
            fib[i] = fib[i-1].add(fib[i-2]);
        }
       while(true){
            int x=Integer.parseInt(br.readLine());
            if(x==0)
                break;
            sb.append(fib[x*2-1]).append("\n");
        }
        System.out.print(sb);
    }
}