#include<stdio.h>
    long long calculateTotalCost(int
    quantity[],  int price[], int size) {
    long long totalCost = 0;
    for (int i = 0; i < size; i++) {
        totalCost += (long
        long)quantity[i] * price[i];
    }
    return totalCost;
    }
    int main() {
        int quantity[3], price[3];
        
        for (int i = 0; i <3; i++) {
            scanf("%d %d", &quantity[i],
        &price[i]);
            if (quantity[i] < 0 ||
        price[i] < 0) {
            printf("Invalid
        input\n");
        return 0; // Exit if 
    invalid input
        }
    }
    
    long long totalCost =
    calculationTotalCost(quantity, price, 3);
    printf("lld\n", totalCost); //
    use %lld for long long
    return 0;
    
    }