#include<stdio.h>

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