My simple exponentiation code doesn't work?

Question

My code returns this error:

ERROR! Unhandled Exception: StackOverflowException [ERROR] FATAL UNHANDLED EXCEPTION: System.StackOverflowException: The requested operation caused a stack overflow. at HelloWorld.x (System.Int32 y) <0x41e36180 + 0x00004> in <0e1357c43db845f2b6acb041d1724d28>:0 at HelloWorld.x (System.Int32 y) [0x00001] in <0e1357c43db845f2b6acb041d1724d28>:0 at HelloWorld.x (System.Int32 y) [0x00001] in <0e1357c43db845f2b6acb041d1724d28>:0 at HelloWorld.x (System.Int32 y) [0x00001] in at HelloWorld.x (System.Int32 y) [0x00001] in <0e1357c43db845f2b6acb041d1724d28>:0 at HelloWorld.x (System.Int32 y) [0x00001] in <0e1357c43db845f2b6acb041d1724d28>:0 at HelloWorld.x (System.Int32 y) [0x00001] in
[...]
<0e1357c43db845f2b6acb041d1724d28>:0 at HelloWorld.x (System.Int32 y) [0x00001] in <0e1357c43db845f2b6acb041d1724d28>:0 at HelloWorld.x (System.Int32 y) [0x00001] in <0e1357c43db845f2b6acb041d1724d28>:0 at HelloWorld.x (System.Int32 y) [0x00001] in <0e1357c43db845f2b6acb041d1724d28>:0 at HelloWorld.x (System.Int32 y) [0 etc...

I tried everything i swear and nothing worked.

My code:

using System;

public class HelloWorld

{
    static int x(int y)
    {
        return x(y)*x(y)+y;
    }

    public static void Main(string[] args)
    {
        Console.WriteLine (x(1));
    }
}