// editor4
#include<stdio.h>
int main()
{ 
    int x,y,z;
    int a,b,c;
    scanf("%d %d",&x,&a);
    scanf("%d %d",&y,&b);
    scanf("%d %d",&z,&c);
    if(x<=0 || a<=0)
    {
    printf("invalid input");
    }
    else
    }
        printf("%d",x*a+y*b+z*c);
    }
}