#include<stdio.h>
int main(){
   int quantity_x, price_x;
   int quntity_y, price_y;
   int quantity_z, price_z;
   
   scanf("%d %d",&quantity_x,&price_x);
   scanf("%d %d",&quantity_y,&price_y);
   scanf("%d %d",&quantity_z,&price_z);
    
    if(quntity_x<0||price_x<0||quantity_y<0||price_y<0||quantity_z<0||price_z<0){
        printf("Invalid input\n");
        
    }
    else{
        long long total_cost=(long long)quantity_x*price_x+(long long)quantity_y*price_y+(long long)quantity_z*price_z;
        printf("%11d\d",total_cost);
    }