#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
const auto INF = 0x3f3f3f3f;
const int N = 1e5 + 5;
int a[3][3];
int main() {
  int n;
  scanf("%d", &n);
  memset(a, INF, sizeof(a));
  scanf("%d", &a[0][1]);
  a[1][0] = a[0][1];
  scanf("%d", &a[0][2]);
  a[2][0] = a[0][2];
  scanf("%d", &a[1][2]);
  a[2][1] = a[1][2];
  n--;
  int sum = 0, pos = 0;
  while (n--) {
    int minn = INF, nee = 0;
    for (int i = 0; i < 3; i++) {
      if (minn > a[pos][i]) {
        minn = a[pos][i];
        nee = i;
      }
    }
    sum += minn;
    pos = nee;
  }
  cout << sum << endl;
}
