#include<stdio.h>

int main(void) {
	int d, a, b, minCost, cost;
	scanf("%d", &d);
	scanf("%d%d", &a, &b);
	minCost = d * b;
	for (int x = 0; x <= d; x++) {
		cost = x * a + (d - x)*b;
		if (minCost > cost) {
			minCost = cost;
		}
	}
	printf("%d", minCost);
	return(0);
}