#include<stdio.h>
int main()
{
    int X,x;
    int Y,y;
    int Z,z;
    scanf("%d",&X,&x);
    scanf("%d",&Y,&y);
    scanf("%d",&Z,&z);
    if(X<0 ||x<0 || Y<0 ||y<0 || Z<0 || z<0)
    printf("Invalid input");
    else
    printf("%d",x+y+z);
    return 0;
}