#include <bits/stdc++.h>
using namespace std;
long double PI = acosl(-1);
long long int power(long long int b, long long int p) {
  long long int mul = 1;
  for (long long int i = 1; i <= p; i++) {
    mul *= b;
  }
  return mul;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int i = 0, j = 0, c = 0, k = 0, n = 0, w, d = 0, f1 = 0, s = 0,
                sum = 0, t = 0, m = 0, l = 0, r = 0, x = 0, u, u1;
  cin >> n >> m >> c >> d;
  vector<long long int> v;
  c = min(m, c);
  n--;
  if (n >= 1) {
    sum += c;
    c = min(c, d);
    n--;
  }
  cout << sum + (c * n) << endl;
  return 0;
}
