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