public static int equalStacks(List<int> h1, List<int> h2, List<int> h3)
    {
        int sum1 = h1.Sum();
        int h1Index = 0;
        int sum2 = h2.Sum();
        int h2Index = 0;
        int sum3 = h3.Sum();
        int h3Index = 0;
        
        if (sum1 == 0 || sum2 == 0 || sum3 == 0) return 0;
        while (sum1 != sum2 || sum2 != sum3 || sum1 != sum3) {
            if (h1Index >= h1.Count() || h2Index >= h2.Count() 
                || h3Index >= h3.Count()) return 0;
                
            int max = (int)Math.Max(Math.Max(sum1, sum2), sum3);
            if (sum1 == max)
                sum1 -= h1[h1Index++];
            else if (sum2 == max)
                sum2 -= h2[h2Index++];
            else
                sum3 -= h3[h3Index++];
        }
        return sum1;
    }