#include <stdio.h>
int main()
{
	int n;
	char a[21][50] = 
	{"1","1","2","6","24","120","720","5040","40320","362880","3628800",
		"39916800","479001600","6227020800","87178291200","1307674368000","20922789888000","355687428096000","6402373705728000","121645100408832000","2432902008176640000"
	};
	while(scanf("%d",&n) != EOF){
		printf("%s\n",a[n]);
	}
	return 0;
}