// 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",&quantityx,&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;
}