#include <iostream>

using namespace std;

int main()

{

int a;

cin >> a;

if( a > 0) a = a * 2;

else a = a / 2;

cout << a;

return 0;

}

#include <iostream>

using namespace std;

int main(){

cout.precision(10);

double a;

cin>>a;

if (a>0) a*=2; else a/=2;

cout<<a;

return 0;

}