#include<iostream>

using namespace std;

typedef long long LL;

LL n;
LL sum=1;
LL fac(LL u)
{
    if(u==n)
    {
        return sum*u;
    }
    sum=sum*u;
    fac(u+1);
}

int main()
{
    cin>>n;
    cout<<fac(1)<<endl;
    return 0;
}