#include<sstdio.h>
int main(){
    int q1, p1, q2, p2,q3, p3;
    if (scanf("%d %d %d %d %d %d", &q1, &p1, &q2, &p2,&q3, &p3)!=6){
        printf("Invalid input\n");
    } else if (q1 < 0|| p1 < 0|| q2 < 0 || p2 < 0 || q3 < 0 || p3 < 0){
        printf("Invalid input\n");
    } else {
        long long total = (long long)q1 * p1 + (long long)q2 * p2 +( long long
        q3 * p3;
        printf("%11d\n", total);
    }
    return 0;
}