#include <stdio.h>
int main ()
{
    int pricex, priceY, priceZ, qunatityX, qunatityY, qunatityZ;
    if(scanf ("%d %d", &qunatityX, &priceX) ==2 && quantityX>0 && prizeX>0) &&
       scanf ("%d %d", &qunatityY, &priceY) ==2 && quantityY>0 && prizeY>0) &&
       scanf ("%d %d", &qunatityZ, &priceZ) ==2 && quantityZ>0 && prizeZ>0)
    )
    {
    printf("%d",((qunatityX*prizeX)+(qunatityY*prizeY)+(qunatityZ*prizeZ)));
    }
    else
    {
        printf("Invalid input");
    }
    return 0;
}