#include <iostream>
#include <vector>
#include <climits>
using namespace std;
int dp[100020];
int main(){
  int n,c,v;cin>>n>>c>>v;
  for(int i = 0; n >= i; i++){
    dp[i] = 1000000000;
  }
  dp[1] = 0;
  for(int i = 1; n >= i; i++){
    int x = 1;
    for(int j = i+i; n >= j-i; j+=i){
      dp[min(n,j)] = min(dp[min(n,j)],dp[i]+c+v*x);
      x++;
    }
  }
  cout << dp[n] << endl;
}