#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>
#include<bitset>
#include<cassert>
#include<complex>
#include<fstream>
#include<cstdlib>
#include<functional>
#include<array>
using namespace std;
typedef long long ll;
const int mod=998244353;
const int dx[]={1,0,0,-1},dy[]={0,1,-1,0};
typedef pair<ll,ll>P;
int tmp[200000];
int main(){
	ll n;
	int a,b;
	cin>>n>>a>>b;
	ll ans=-(n-1)*a-n%2*b;
	if(n%2==0&&a<b)
		ans-=(b-a)*2;
	if(a*2<b)
		ans=(n-1)*a-n*b;
	cout<<ans<<endl;
}