下面程序运行后输入4，输出结果应是
#include <iostream>
using namespace std;
int fac (int n)
{
if (n <=1)
return 1;
else
return n * fac (n - 1);
}
int main ()
{
int n = 0;
cin >> n;
int ret = fac (n);
cout << ret;
return 0;
}
4
12
24
48