public Roman Lower(Roman number)
{
Roman previous = null;
foreach (Roman r in romans)
if (r == number)
return previous;
else
previous = r;
return null;
}
public Roman Higher(Roman number)
{
bool isNext = false;
foreach (Roman r in romans)
if (isNext)
return r;
else
if (r == number)
isNext = true;
return null;
}