#include <bits/stdc++.h>
using namespace std;

int main(){
  int d, a, b;
  cin >> d >> a >> b;
  
  int ans = 1e9;
  for(int x = 0; x <= d; x++){
    ans = min(ans, x * a + (d - x) * b);
  }
  
  cout << ans;
}