#include<stdio.h>
int main() {
    int qtyX,priveX;
    int qtyY,priceY;
    int qtyZ,priceZ;
    long totalCost;
    scanf("%d %d", &qtyX, &priceX);
    scanf("%d %d", &qtyY, &priceY);
    scanf("%d %d", &qtyZ, &priceZ);
    if (qtyX < 0 || qtyY < 0 || qtyZ < 0 || priceX < 0 || priceY < 0 || priceZ < 0){
        printf("Invalid input");
        return 0;
    }
    if (qtyX > 10000 || qtyY > 10000 || qtyZ > 10000 || priceX > 10000 priceY > 10000 || priceZ > 10000) {
        printf("Invalid input");
        return 0;
    }
    totalCost=(qtyX*priceX)+(qtyY*priceY)+(qtyz*priceZ);
    printf("%ld", totalCost);
    return 0;
}