题目描述：
源码：
#include"iostream"
using namespace std;
int main()
{
int n, digit, carry, tmp;
int a[40000];
while(cin>>n)
{
if(n <= 1)
{
cout<<1<<endl;
}
else
{
a[0] = 1;
digit = 1;
for(int i = 2; i <= n; i++)
{
carry = 0;
for(int j = 0; j < digit; j++)
{
tmp = a[j] * i + carry;
a[j] = tmp % 10;
carry = tmp / 10;
}
while(carry > 0)
{
a[digit] = carry % 10;
digit++;
carry /= 10;
}
}
for(int j = digit - 1; j >= 0; j--)
{
cout<<a[j];
}
cout<<endl;
}
}
return 0;
}