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

int main(){
    int d,a,b;
    long long ans = 1000000000000;
    int printans = 0;
    cin >> d >> a >> b;
    for(int i = 0; i <= d; ++i){
        if(i*a + (d-i)*b < ans){
            printans = i;
        }
    }
    cout << printans*a + (d-printans)*b << endl;
}