#include<algorithm>
using namespace std;
int n,m,a[100001],nrsol[100001];
void solve(){
    int i,j;
    scanf("%d%d",&n,&m);
    for(i=1; i<=m; ++i)
        scanf("%d",&a[i]);
    for(i=m+1,nrsol[m]=1; i<=n; ++i)
        nrsol[i]=(i-1)*nrsol[i-1];
    printf("%d",nrsol[n]);}
int main(){
    freopen("grigo.in","r",stdin);
    freopen("grigo.out","w",stdout);
    solve();
    return 0;}