#include<stdio.h>
int cal_total(int qa,int pa,int qb,intpb,int qc,int pc)
{
    return (qa*pa) + (qb*pb) + (qc*pc);
}
int main()
{
    int qa,pa,qb,pb,qc,pc;
    scanf("%d %d",&qa,&pa);
    scanf("%d %d",&qb,&pb);
    scanf("%d %d",&qc,&pc);
    if(qa<0 || pa<0 || qb<0 || pb<0 || qc<0 || pc<0)
    {
        printf("Invalid input")
        return 0;
    }
    int total = cal_total(qa,pa,qb,pb,qc,pc);
    printf("%d",total);
    return 0;
}