#include <iostream>
using namespace std;

const int INF = (1 << 28);

int dp[50010];

int main() {
    int N, C, V;
    cin >> N >> C >> V;
    
    fill(dp, dp + 50010, INF);
    dp[1] = 0;

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

    return 0;
}