#include<stdio.h>
void main()
{
long fac(int n);
int n;
long fact=0;
printf("please enter a integer number:\n");
scanf("%d\n",&n);
fact=fac(n);
printf("%d!=%ld\n",n,fact);
}
long fact(int n)
{
int i;
long fact=1;
for(i=1;i<=n;i++)
fac=fac*1;
return(fac);
}