#include <stdio.h>
void main() {
    int qtyX, priceX, qtyY, priceY, qtyZ, priceZ;
    
    if (scanf("%d %d", &quantityX, &priceX) != 2 || scanf("%d %d", &quantityY, &priceY) != 2 || scanf("%d %d", &quantityZ, &priceZ) != 2) {
            printf("Invalid input\n");
    }
        
    if (quantityX < 0 || priceX < 0 || quantityY < 0 || priceY < 0 || quantityZ < 0 || priceZ < 0) {
        printf("Invalid input\n");
    }    
    
    int totalCost = (quantityX * priceX) + (quantityY * priceY) + (quantityZ * priceZ);
    
    printf("%d\n", totalCost);
}