#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i < (int)(n+1); i++)
#define repn(i,a,b) for (int i = (int)(a) ; i < (int)(b+1); i++)
#define repv(i, n) for (int i = (int)(n-1); i >= 0; i--)
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define sz(x) ((int)(x).size())
#define cauto const auto&
#define bit(n) (1LL<<(n))
#define uni(v) v.erase( unique(v.begin(), v.end()), v.end() );
using ll = long long;
using P = pair<int,int>;
using PP = pair<int, P>;
using Graph = vector<vector<int>>;
#ifdef LOCAL
    #include <debug.hpp>
    #define debug(...) debug::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
    #define debug(...) (static_cast<void>(0))
#endif

int main(){
    ll n,a,b;
    cin >> n >> a >> b;
    ll ans =0;
    if(n%2== 1){
        ans = (n-1)*a + b;
    } else {
        ans = (n-1)*a;
    }
    if(n%2 == 0){
        ans = max(ans,b * n-a*(n-1));
        if(n%2 == 1){
            ll tmp = ans - 2*a + 2 * b;
            ans = max(ans,tmp); 
        }
    } 
    cout << -ans << endl;
    return 0;
}