#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<ll,ll>;
#define fix(x) fixed << setprecision(x)
#define asc(x) x, vector<x>, greater<x>
#define rep(i, n) for(ll i = 0; i < n; i++)
#define all(x) (x).begin(),(x).end()
template<class T>bool chmin(T&a, const T&b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool chmax(T&a, const T&b){if(a<b){a=b;return 1;}return 0;}
ll n,a,b;
ll f(ll x){
    return a*(n-1-x*4)-b*(n-2*x);
}
int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cin >> n >> a >> b;
    if(b-2*a<=0) cout << f(n/2) << '\n';
    else cout << f(0) << '\n';
    return 0;
}