#include <bits/stdc++.h>
using namespace std;
const int MAXN = 20;
int state,n;
int lowbit(int x){ 
    return x&-x;
}
int onecon(int x){
    int cnt=0;
    while(x){
        x-=lowbit(x);
        cnt++;
    }
    return cnt;
}
long long f[21][1<<MAXN];
int main(){
	freopen("rook.in","r",stdin);
	freopen("rook.out","w",stdout);
    scanf("%d",&n);
    state=(1<<n)-1;
    f[0][0]=1;
    for(int i=1;i<=n;i++){
        for(int j=0;j<=state;j++){
            if(onecon(j)==i){
//				cout<<"qwq"<<endl,
				for(int k=0;k<n;k++){
                    if((1<<k)&j)
                    f[i][j]+=f[i-1][j-(1<<k)];
                }
            }
        }
    } 
    cout<<f[n][state];
    return 0;
}