#include<stdio.h>
int main()
{
    int qtyX, priceX;
    int qtyY, priceY;
    int qtyZ, pricez;
    if(scanf("%d %d", &qtyX, &priceX) !=2 || scanf("%d %d", &qtyY, &priceY) != 2 || scanf("%d %d", &qtyZ, &priceZ) !=2)
    {
        printf ("Invalid input");
        return 0;
    }
    if (qtyX <0 ||priceX <0 || qtyY <0 ||priceY <0 || qtyZ <0 || priceZ <0);
    {
        printf("Invalid input");
        return 0;
    }
    long total = (qtyX * priceX)+(qtyY * priceY)+(qtyZ * priceZ);
    printf("%ld", total);
    retrn 0;
}