private void SubtractThatPossible(List<int> abacus) { for (int i = 0; i < abacus.Count - 1; i++) { if (abacus[i] < abacus[i + 1]) { abacus[i] = abacus[i + 1] - abacus[i]; abacus.RemoveAt(i + 1); i = abacus.Count; } } }