#include <math.h>
#include <stdio.h>
int main() {
	int N, C, V;
	scanf("%d %d %d", &N, &C, &V);
	int ret = 1 << 30;
	for(int X = 1; 1 << X <= 2 * N; X++) {
		int a = pow(N + 1.0e-9, 1.0 / X);
		int Y = (log(N) - X * log(a)) / (log(a + 1) - log(a)) + 1 - 1.0e-9;
		int cost = X * C + (X * (a - 1) + Y) * V;
		if(ret > cost) ret = cost;
	}
	printf("%d\n", ret);
	return 0;
}