#include<stdio.h>
int sl(int n){
	if(n==1){
	return 1;}else if(n==2){
		return 2;
	}
	else{
		return sl(n-1)*2-sl(n-2)+1;
} 
}
int main()
{
	int n,i,s=0;
	scanf("%d",&n);
	for(i=1;i<=n;i++){
		s=s+sl(i);
	}
	printf("%d",s);
return 0;
}

/**************************************************************
	Problem: 1145
	User: admin
	Language: C
	Result: Accepted
	Time:10 ms
	Memory:1144 kb
****************************************************************/