problem with console app

here is a relevent snippets

Code:

TCHAR buf[20]; 

fdwMode = ENABLE_LINE_INPUT |       //ReadConsole() should wait and read 
                                   // characters until ENTER is pressed 
                 ENABLE_ECHO_INPUT |   // show characters as you type 
                 ENABLE_PROCESSED_INPUT;    // let system process all 
                                                // control keystrikes 
SetConsoleMode(hStdin, fdwMode) ; 
        
fdwMode = ENABLE_PROCESSED_OUTPUT; 
SetConsoleMode(hStdout, fdwMode); 


while (1) 
{ 
    WriteConsole(hStdout, "\npress [1] for codepage: ", 25, &ch, NULL); 
     ReadConsole(hStdin,buf,1,&ch,NULL); 
     buf[ch]='\0'; 
     FlushConsoleInputBuffer(hStdin); 
    WriteConsole(hStdout, buf, 3, &ch, NULL); 
}

the problem is that the first time while executes everything is ok:
i get on screen:

press [1] for codepage:

i enter 1 and press enter then it prints the character.

from this point something strange happens...
while loop continue to execute two more times despite the fact that ReadConsole() should wait for input...

anyone understand where is the problem?