import java.math.BigInteger;
public class Factorials {
public static BigInteger fac;
public static BigInteger two = BigInteger.valueOf(2);
static BigInteger mul(BigInteger start, BigInteger mid, BigInteger end) {
if(start == mid && mid == end) {
return Factorials.fac.subtract(start);
} else {
return Factorials.mul(start, start.add(mid.subtract(start).divide(Factorials.two)), mid).multiply(Factorials.mul(mid, mid.add(end.subtract(mid).divide(Factorials.two)), end));