How does **Select(int.Parse)** work in such Linq expression?

```
"1,2,3,4,5".Split(',').Select(int.Parse).ToList();                 //ok
"1,2,3,4,5".Split(',').Select(x => int.Parse(x)).ToList();         //ok

```

Why example with Console.Writeline returns compilation error?

```
"1,2,3,4,5".Split(',').Select(Console.WriteLine).ToList();         //error
"1,2,3,4,5".Split(',').Select(x => Console.WriteLine(x)).ToList(); //ok

```

When it is allowed to omit lambda like (x => ....(x))