int main()
{
    int i=0,b=0;
    while(1)
    {
        i=i+1;
        int a[i];
        scanf("%d",&a[i]);
        if(a[i]!=-1)
        {
            b=b+a[i];
        }
        else
        {
            break;
        }
    }
    printf("%d",b);
    return 0;
}