#include<bits/stdc++.h>
#define ll long long
#define in(A,N); int A[N]; for(int z=0;z<N;z++){cin>>A[z];}
#define pt(A,N); for(int z=0;z<N;z++){cout<<A[z]<<" ";} cout<<endl;
#define add(a,b,c) for(int z=0;z<b;z++){c+=a[z];}
using namespace std;
int main()
{ll N;
cin>>N;
cout<<N*2-1<<endl;

return 0;
}