#include<bits/stdc++.h>

using namespace std;

typedef long long int64;
const int64 INF = 1LL << 60;


int main()
{
  int N, C, V;
  cin >> N >> C >> V;

  int64 dp[50001];
  fill_n(dp, 50001, INF);
  dp[1] = C;
  for(int i = 1; i <= N; i++) {
    int cost = V;
    for(int j = i + i;; j += i, cost += V) {
      dp[min(j, N)] = min(dp[min(j, N)], dp[i] + cost + C);
      if(j >= N) break;
    }
  }

  cout << dp[N] - C << endl;
}