/*
編寫一個方法,求整數n的階乘,例如5的階乘是1*2*3*4*5
*/
public class Test1
{
public static void main(String[] args){
java.util.Scanner s = new java.util.Scanner(System.in);
int i = s.nextInt();
int n;
n = Test1.Factorial(i);
System.out.println(n);
}
public static int Factorial(int i){
int sum = 1;
for(int j = 1;j <= i;j++)
sum *= j;
return sum;
}
}