#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 = 2; i <= N; i++) {
    for(int j = 1; j < i; j++) {
      dp[i] = min(dp[i], dp[j] + (i - j + j - 1) / j * V + C);
    }
  }
  cout << dp[N] - C << endl;
}