UVA - 10223 - How many nodes ?

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 {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuffer sb = new StringBuffer("");
        BigInteger[] catlan = new BigInteger[37];
        BigInteger[] fact = new BigInteger[73];
        fact[0] = BigInteger.ONE;
        fact[1] = BigInteger.ONE;
        for (int i = 2; i < fact.length; i++) {
            fact[i] = fact[i - 1].multiply(BigInteger.valueOf(i));
        }
        int oof = 0;
        for (int i = 0; i < catlan.length; i++) {
            catlan[i] = fact[2 * i].divide(fact[i + 1].multiply(fact[i]));
        }
        String m = "";
        while ((m = br.readLine()) != null) {
            int n = Integer.parseInt(m);
            int ind = -1;
            for (int i = 1; i < catlan.length; i++) {
                if (BigInteger.valueOf(n).compareTo(catlan[i]) == 0) {
                    ind = i;
                    break;
                }
            }
            sb.append(ind).append("\n");
        }
        System.out.print(sb);
    }
}