#include "iostream"
#include "climits"
#include "list"
#include "queue"
#include "stack"
#include "set"
#include "functional"
#include "algorithm"
#include "string"
#include "map"
#include "iomanip"
#include "random"

using namespace std;
const long long int MOD = 1000000007;
const long double EPS = 0.00000001;

long long int N, M, K, Q, W, H, L, R;
long long int ans;


int main() {
	ios::sync_with_stdio(false);
	cin >> N;
	cin >> K >> Q;
	ans = 1000000000;
	long long int box = 1;
	long long int bag = 1;
	for (int i = 1; i < N; i++) {
		box = 1;
		long long int c = 0;
		while (box < N) {
			bag = box;
			c += K;
			for (int j = 0; j < i; j++) {
				box += bag;
				c += Q;
				if (box >= N)break;
			}
			if (box >= N)break;
			ans = min(ans, c + ((N-box)/bag+!!((N-box)%bag))*Q);
			//cout << ans << endl;
		}
		ans = min(ans, c);
	}
	cout << ans << endl;
	return 0;
}