#include <iostream>
#include <cassert>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  long d; cin >> d;
  long a, b; cin >> a >> b;
  long ans = 1e18;
  for (long x = 0; x <= d; x++) {
    ans = min(ans, x * a + (d - x) * b);
  }
  cout << ans << endl;
  return 0;
}