StdIn not working... @ Linux

StdIn not working... @ Linux

Below is the program.. I tried after moving jars also... Is moving enough
? or any extra task to do with the jar files .
public class Stack {
public static void main(String[] args) {
while (!StdIn.isEmpty()) {
}
}
}
i moved necessary jar(stdlib.jar,algs4.jar ) files to lib ..... But it
still showing the error.......
Stack.java:4: error: cannot find symbol while (!StdIn.isEmpty()) { ^
symbol: variable StdIn location: class Stack 1 error
Thanks in advance :)