#include <stdio.h>
int main ()
{
    int priceX, priceY, priceZ, qunatityX, qunatityY, qunatityZ;
    scanf ("%d %d", &qunatityX, &priceX,&qunatityY, &priceY, &qunatityZ , &priceZ ) ;
    if(qunatityX<0 || priceX<0 || qunatityY<0 || priceY<0 || qunatityZ<0 || priceZ<0)
    {
        printf("Invalid input");
    }
      else
      {
          int totalCost = (qunatityX*priceX)+(qunatityY*priceY)+(qunatityZ*priceZ);
       printf("%d", totalCost);
      }
    return 0;
}