Java Programming-Factorial

import java.io.*;
class factorial
{
public static void main(String args[])throws IOException
{
String a;
int n,sum,i;
sum=1;
System.out.print("ENTER A INTEGER NUMBER:");
BufferedReader obj=new BufferedReader(new InputStreamReader(System.in));
a=obj.readLine();
n=Integer.parseInt(a);
for(i=1;i<=n;i++)
{
sum=sum*i;
}
System.out.print("sum is="+sum);
System.out.print("\n");

}
}