#include<stdio.h>
int main()
{
    int qtyX,priceX,qtyY,pricey,qtyZ,priceZ;
    
    if(scanf("%d %d", &qtyX,&'price'X) != 2||
       scanf("%d %d", &qtyY,&'price'Y) != 2||
       scanf("%d %d", &qtyZ,&'price'Z) != 2||{
       printf("Invalid input");
       return 0;
}


if(qtyX < 0 || qtyY < 0||qtyZ < 0 || priCEX < 0 || priceY < 0 || price < 0)
{
    printf("Invalid input");
    return 0;
}

long totalcost =(qtyX * priceX) +(qtyY * priceY) +
(qtyZ *priceZ);
printf("%ld", totalcost);


return 0;
}