//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
#define rep(i, n) for(int i=0; i<n; ++i)
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
using namespace std;
using ll = int64_t;
using ld = long double;
using P = pair<int, int>;
using vs = vector<string>;
using vi = vector<int>;
using vvi = vector<vi>;
template<class T> using PQ = priority_queue<T>;
template<class T> using PQG = priority_queue<T, vector<T>, greater<T> >;
const int INF = 100010001;
const ll LINF = (ll)INF*INF*10;
template<typename T1, typename T2>
inline bool chmax(T1 &a, T2 b) {return a < b && (a = b, true);}
template<typename T1, typename T2>
inline bool chmin(T1 &a, T2 b) {return a > b && (a = b, true);}
template<typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) { return is >> p.first >> p.second;}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) { return os << p.first << ' ' << p.second;}

const int N = 5e4+10;

//head

int n, c, v;
int dp[N];

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> c >> v;
  fill(dp, dp+n, 1e9);

  for(int i = n; i > 1; i--) if(dp[i] != (int)1e9) {
    int nn = -1;
    for(int u = 2;; u++) {
      int h = (i+u-1)/u;
      chmin(dp[h], dp[i]+c+v*u-v);
      if(abs(h-nn) < 2) {
        break;
      }
      nn = h;
    }
    for(int u = 1; u < nn; u++) {
      int h = (i+u-1)/u;
      chmin(dp[u], dp[i]+c+v*h-v);
    }
  }

  cout << dp[1] << endl;
}