#define _USE_MATH_DEFINES #include<iostream> #include<vector> #include<algorithm> #include<cmath> #include<string> #include<iomanip> #include<numeric> #include<queue> #include<deque> #include<stack> #include<set> #include<map> #include<random> using namespace std; typedef long long ll; const int mod=998244353; int main(){ int n; cin>>n; cout<<n/2*2<<endl; }