#include<stdio.h>
int main() {
    int q1, p1, q2, p2, q3,  p3;
    if (scanf("%d %d", &q1, &p1) != 2 ||
        scanf("%d %d", &q2, &p2) != 2 ||
        scanf("%d %d", &q3, &p3) != 2  {
        printf("Invalid input\n");
        return 0;
    }
    if (q1 < 0 || p1 < 0 || q2 < 0 || p2 < 0 || q3 < 0 || p3 < 0) {
        printf("Invalid input\n");
    } else {
        int total = q1 * p1 + q2 * p2 + q3 * p3;
        printf("%d\n", total);
    }    
    return 0;
}