코드 :
import java.math.BigInteger;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
BigInteger num = new BigInteger("1");
BigInteger ii = new BigInteger("1");
int n = scan.nextInt();
for (int i = 0; i < n; i++) {
num = num.multiply(ii);
ii = ii.add(new BigInteger("1"));
}
System.out.println(n + "!=" + num);
}
}