I don't understand why it isn't correct.
package pl.codegym.task.task15.task1531;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigDecimal;
/*
Silnia
*/
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) {
if (n <= 0) {
return "1";
} else {
long result = 1;
for (int i = 1; i <= n; i++) {
result *= i;
}
return Long.toString(result);
}
}
}