...
package com.javarush.task.task15.task1531;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigDecimal;
/*
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) {
int a = 1 ;
if(n>0){
for(int i = 1; n>=i;i++){
a*=i;
}
}
else if(n==0) {
a = 1;
}
else{
a = 0;
}
;
return Integer.toString(a);
}
}