// editor4
#include<stdio.h>
int main()
{
    int quantityX,quantityY,quantityZ;
    int priceX,priceY,priceZ;
    int total;
    scanf("%d %d",&quantityX,&priceX);
    scanf("%d %d",&quantityY,&priceY);
    scanf("%d %d",&quantityZ,&priceZ);
    if(quantityX<0 || quantityY<0 || quantityZ<0 || priceX<0 || priceY<0 || priceZ<0)
    {
        printf("Invalid input");
    }
    else
    {
        total=quantityX*pricex+quantityY*priceY+quantityZ*priceZ;
        printf("%d",total);
    }
    
    
    
    
    
    
    
    
    
    return 0;
}