#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <cmath>
#include <iomanip>
#include <bitset>
#include <functional>
#include <queue>
#include <stack>
#include <list>
#include <deque>
#include <utility>
#include <numeric>
#include <set>
#include <map>
#include <complex>
#include <cctype>
#include <climits>
#include <cassert>
#include <unordered_map>
#include <unordered_set>
#include <time.h>

using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
using uint = unsigned;
using vi = vector<int>;
using vl = vector<long>;
using vll = vector<long long>;
using vd = vector<double>;
using vvi = vector<vi>;
using vvl = vector<vl>;
using vvll = vector<vll>;
using vc = vector<char>;
using vs = vector<string>;
using vb = vector<bool>;
using pii = pair<int, int>;
using pcc = pair<char, char>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;
using vpii = vector<pii>;
using vpll = vector<pll>;

typedef complex<double> xy_t;

#define rep(i, n) for (ll i = 0; i < ll(n); i++)
#define repback(i, n) for (ll i = n-1; i >= 0; i--)
#define REP(i, a, b) for (ll i = a; i < ll(b); i++)
#define REPBACK(i, a, b) for (ll i = a-1; i >= ll(b); i--)
#define all(x) (x).begin(), (x).end()
#define debug(x) cout << "debug:" << x << endl

static const double pi = acos(-1.0);
const long long INFL = pow(10,18);
const long long INFLMAX = 9223372036854775807;
const int INF = pow(10,9);
const int INFMAX = 2147483647;
const int mod1 = 1000000007;
const int mod2 = 998244353;
const vi dx = {1,0,-1,0};
const vi dy = {0,1,0,-1};
const vi dx2 = {0, 1, 0, -1, 1, -1, 1, -1};
const vi dy2 = {1, 0, -1, 0, 1, 1, -1, -1};


int main(){
    ll N,A,B; cin >> N >> A >> B;
    
    if(B >= 2*A) cout << A*(N-1) - B*N << endl;
    else{
        if(N % 2 == 1) cout <<(-1)*A*(N-1) - B << endl;
        else{
            if(A >= B) cout << (-1)*A*(N-1) << endl;
            else cout << (-1)*A*(N-3) - 2*B << endl;
        }
    }
}