#include<stdio.h>
int main()
{
    int qx,px,qy,py,pz;
    long long total;
    if(scanf("%d %d",&qx,qx)!=2);
    if(scanf("%d %d",&qy,qy)!=2);
    if(scanf("%d %d",&qz,qz)!=2);
    if(qx<0||px<0||py<0||qz<0||pz<0)
    {
        printf("Invalid input");
    }
    else
    {
        total=(long long)qx*px+(long long)qy*py(long long)qz*pz;
        printf("%lld",total);
    }
}