#include <stdio.h>
int main() {
    int xq, xp, yq, yp, zq, zp ;
    if(scanf("%d%d",&xq, &xp)!=2) ||
        (scanf("%d%d", &yq, &yp)!=2) ||
        (scanf("%d%d", &zq, &zp)){
        printf("Invalid input");
        return 0;
    }
    int total=((xq*xp)+(yq*yp)+(zq*zp));
    if(xq>0 && xp>0 && yq>0 && qp>0 && zq>0 && zp>0){
        printf("%d", total);
    }
    else {
        printf("Invalid input");
    }
    return 0;
}