#include<stdio.h>
int main()
{
int aX,ax,bY,by,cZ,cz,Total;
scanf("%d %d",&aX,&ax);
scanf("%d %d",&bY,&by);
scanf("%d %d",&cZ,&cz);
if(aX0 || ax0 || bY<0 || by<0 || cZ<0 || cz<0)
{
    printf("Invalid input");
}
else{
    Total=(aX*ax)+(bY*by)+(cZ*cz);
    printf("%d",Total);
}
return 0;
}