#include <bits/stdc++.h>
using namespace std;
int n, a, b, c, mn;
int dpt[5];
void dp(int i, int total, int stage) {
  if (i == n) {
    mn = min(total, mn);
    return;
  }
  if (stage == 0) {
    if (a <= b)
      dp(i + 1, total + a, 1);
    else
      dp(i + 1, total + b, 2);
  }
  if (stage == 1) {
    if (a <= c)
      dp(i + 1, total + a, 0);
    else
      dp(i + 1, total + c, 2);
  }
  if (stage == 2) {
    if (b <= c)
      dp(i + 1, total + b, 0);
    else
      dp(i + 1, total + c, 1);
  }
}
int main() {
  while (scanf("%d", &n) != EOF) {
    scanf("%d %d %d", &a, &b, &c);
    mn = 123456789;
    dpt[0] = -1, dpt[1] = -1, dpt[2] = -1;
    dp(1, 0, 0);
    printf("%d\n", mn);
  }
  return 0;
}
