#include <bits/stdc++.h>
using namespace std;

long long N, A, B;

int main() {
    cin >> N >> A >> B;
    if (2*A < B) {
        cout << (A-B)*N-A << endl;
    } else {
        long long b = N/2;
        cout << A*(N-4*b-1)-B*(N-2*b) << endl;
    }
}