whats wrong with my code

import java.io.*;
public class Contohif {
public static void main (String[]args) {
BufferedReader input = newBufferedReader (new InputStreamReader)(System.in));
try {
System.out.print("Nilai ujian Anda: ");
String at = input.readLine();
int nilaiUjian = Integer.valueOf(st).intValue();
char hurufMutu;

if (nilaiUjian >= 80)
{
hurufMutu = 'A';
}
else
if (nilaiUjian >= 65)
{
hurufMutu = 'B';
}
else
if (nilaiUjian >= 55)
{
hurufMutu = 'C';
}
else
if (nilaiUjian >= 45)
{
hurufMutu = 'D';
}
else {
hurufMutu = 'E';
}
System.out.println("Huruf Mutu" + hurufMutu);
}
catch (Exception.e)
{
}
}
}

 

A parser would show you that line 4 has an extra closing paren. Did your compiler not give you an error message?