#include <algorithm>
#include <cstdio>
#include <vector>
#define repeat_from(i, m, n) for (int i = (m); (i) < int(n); ++(i))
using namespace std;
template <class T> inline void setmin(T & a, T const & b) { a = min(a, b); }

constexpr int inf = 1e9+7;
int main() {
    int n, c, v; scanf("%d%d%d", &n, &c, &v);
    vector<int> dp(2 * n + 1, inf);
    dp[1] = 0;
    repeat_from (x, 1, dp.size()) {
        for (int k = 1; x + k * x < dp.size(); ++ k) {
            setmin(dp[x + k * x], dp[x] + c + k * v);
        }
    }
    printf("%d\n", *min_element(dp.begin() + n, dp.end()));
    return 0;
}