#include <fstream>

using namespace std;
ifstream in("grigo.in");
ofstream out("grigo.out");
int main()
{
    int n,m,i,j,f=1;
    in>>n>>m>>i>>j;
    for(i=1;i<n;++i)
        f*=i;
    out<<f;
    return 0;
}