#include<bits/stdc++.h> using namespace std; int n,f[31],g[31],x=-2; int main() { f[0]=1; cin>>n; for(int i=1;i<=n;i++) { g[i]=g[i-1]*2-x; f[i]=f[i-1]+g[i]; f[i]-=!(f[i]%2); x+=1; } cout<<f[n]; return 0; }