#include<iostream>
using namespace std;

int main(){
    int n, c, v;
    cin >> n >> c >> v;

    int ans = c+v, len = 2, clip = 1;

    while(len < n){
        if(clip == len || (n-len+clip-1)/clip*v < c+(n-len+clip+len-1)/(clip+len)*v){
            ans += v;
            len += clip;
        }else{
            ans += c;
            clip = len;
        }
    }

    cout << ans << endl;

    return 0;
}