#include <bits/stdc++.h>
using namespace std;

long sumOfGroup(int k) {
   long A[10000000];
   int sum=0;
    for(int i=k;i<=2*k;i++)
    {
        sum=sum+A[i];
     }
return sum;// Return the sum of the elements of the k'th group.
}

int main() {
    int k;
    cin >> k;
    long answer = sumOfGroup(k);
    cout << answer << endl;
    return 0;
}