import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Stack;
public class Main4949 {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
Stack<Character> s;
while(true) {
String str = br.readLine();
if(str.equals(".")){
break;
}
s = new Stack<Character>();
boolean state = true;
for(int i=0; i<str.length(); i++) {
if(str.charAt(i) == '(') {
s.push(str.charAt(i));
}else if(str.charAt(i) == '[') {
s.push(str.charAt(i));
}else if(str.charAt(i) == ')') {
if(s.size() != 0 && s.peek()== '(') s.pop();
else state = false;
}else if(str.charAt(i) == ']') {
if(s.size() != 0 && s.peek() == '[') s.pop();
else state = false;
}
}
if(state && s.size() == 0) {
System.out.println("yes");
}else {
System.out.println("no");
}
}
}
}