#include<stdio.h>
int main()
{
    int quantiityX,quantityY,quantityZ,priceX,priceY,priceZ,Totalcost;
    sacnf("%d %d",&quantityX,&priceX);
    sacnf("%d %d",&quantityY,&priceY);
    sacnf("%d %d",&quantityZ,&priceZ);
    Totalcost=quantityX*priceX+quantityZ*priceZ+quantityY*priceX;
    printf("%d",Totalcost);
    return 0;
}