#include<stdio.h>
int main(){
    int qA,pA,qB,nB,qC,pC;
    scanf("%d %d %d %d %d %d", &qA, &pA, &qB, &pB, &qC, &pC);
    if (qA < 0 || pA < 0 || qB < 0 || pB < 0 || qC < 0 || pC < 0){
        printf("Invalid input\n");
    } else {
        printf("%d\n",(qA * pA) + (qB * pB) + (qC + pC));
    }
    return 0;
}