#include<bits/stdc++.h>
using namespace std;
int main(){
	int sum=0;
	for(int i=1;i<=34;i++){
		sum=sum+1+(i-1)*3;
	}
	cout<<sum;
}
/**************************************************************
	Problem: 1053
	User: linmiaoling
	Language: C++
	Result: Accepted
	Time:3 ms
	Memory:2072 kb
****************************************************************/