#include <bits/stdc++.h>
#define int long long
#define iostream() ios::sync_with_stdio(false),cin.tie(NULL),cout.tie(NULL);
using namespace std;
const int maxn = 1e6+7;
const int MAXN = maxn / 2;
int n;
signed main()
{
    iostream();
    cin >> n;
    //认真研究，我们就会发现：
    cout << n * 2 - 1;
 	return 0;
}