[ 백준 ] 10872- 팩토리얼

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class Main {
    public static int factorial(int num) {
        if(num!=0)
            return num*factorial(num-1);
        else
            return 1;
    }

    public static void main(String[] args) throws IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();

        // 단어 정렬 문제~!
        int N = Integer.parseInt(br.readLine());
        int sum = factorial(N);
        System.out.println(sum);

    }

}