#include <iostream>
#include <vector>
using namespace std;

void chmin(int &a, int x){
    if(a > x) a = x;
}

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

    vector<int> cost(n*2+10, 1001001001);
    cost[1] = 0;
    for(int i = 1; i <= n; i++){
        for(int j = 2; i*j <= n*2; j++){
            chmin(cost[i*j], cost[i]+c+v*(j-1));
        }
    }
    for(int i = n*2; i >= n; i--) chmin(cost[i], cost[i+1]);
    cout << cost[n] << endl;
    return 0;
}