Conversion error.

[Ruby The Roobster]

I don't know any explanation for the following error:
std.conv.ConvException at D:\Programs\D\dmd2\windows\bin\..\..\src\phobos\std\conv.d(2437): Unexpected '\n' when converting from type LockingTextReader to type int

Here is my code for reference:

module main;

import std.stdio;
import std.concurrency;
import core.thread;
import core.stdc.stdlib;
import std.string;
int main(string[] args)
{
     Tid worker;
     int x;
     do
     {
     writeln("Enter in 1 for arabic, 2 for turkish, 0 to quit.");
     readf("%d",x);
     worker = spawn(&Translate_Hello);
     worker.send(x);
     }
     while(x != 0);
	return 0;
}

void Translate_Hello()
{
     int num;
     num = receiveOnly!int();
  switch(num)
   {
     case 1:
         stdout.writeln("مرحبا");
         break;
     case 2:
         stdout.writeln("Merhaba");
         break;
     default:
         stdout.writeln("Invalid Language");
   }
}