Will somebody please tell me what is wrong with this code.
package com.codegym.task.task15.task1531;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
/*
Factorial
*/
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) {
String answer = "";
if (n < 0){
return "0";
}
else if (n == 0){
return "1";
}
else{
BigInteger temp = new BigInteger("1");
for (int i = 1; i <= n; i++) {
temp = temp.multiply(BigInteger.valueOf(n));
}
answer = String.valueOf(temp); //Type.toString(temp);
}
return answer;
}
}