N! java

import java.util.*;
import java.math.*;

public class Num2{
    public static void main(String args[]){
        BigInteger s;
        int n;
        Scanner cin = new Scanner(System.in);
        while(cin.hasNext()){
            n = cin.nextInt();
            s = BigInteger.ONE;
            for(int i = 1; i <= n; i++){
                s = s.multiply(BigInteger.valueOf(i));
            }
            System.out.println(s);
        }
    }
}