static bool IsDistinct(IEnumerable input)
{
var ordered = input.OrderBy(item=>item);

var enumerator =ordered.GetEnumerator();

if(enumerator.MoveNext()==false) return true;

T previous=enumerator.Current;

while(enumerator.MoveNext())
{
T current = enumerator.Current;
if(previous.Equals(current)) return false;
previous = current;
}

return true;

}