#include<iostream>
using namespace std;
long N,A,B;
main()
{
	cin>>N>>A>>B;
	long lc=0,rc=(N-1)/2;
	long ans=A*(N-1)-B*N+(2*B-4*A<0?rc:lc)*(2*B-4*A);
	if(N%2==0)ans=min(ans,A*(-(N-1)));
	cout<<ans<<endl;
}