В чем дело?
package com.javarush.task.task15.task1531;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.*;
/*
Факториал
*/
public class Solution {
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int input = Integer.parseInt(reader.readLine());
reader.close();
System.out.println(factorial(input));
}
public static String factorial(int n) {
//add your code here
if(n<=150) {
if (n <= 0)
return "0";
else if (n == 1)
return "1";
else {
BigInteger first = new BigInteger(String.valueOf(n));
BigInteger second = new BigInteger(String.valueOf(factorial(n - 1)));
BigInteger result = first.multiply(second);
return result.toString();
}
}
else return "";
}
}