#include<iostream>
#include<stack>
#include<string>
using namespace std;
 
int main(){
    string input;
    getline(cin, input);
    stack<char> s;
    while(input != "."){
        for(char alpha : input){
            if(alpha == '['){
                s.push('[');
            }
 
            else if(alpha == ']'){
                if(s.empty()){
                    s.push(']');
                    break;
                }
                else{
                    if(s.top() == '['){
                        s.pop();
                    }
                }
            }
            else if(alpha == '('){
                s.push('(');
            }
            else if(alpha == ')'){
                if(s.empty()){
                    s.push(')');
                    break;
                }
                else{
                    if(s.top() == '('){
                        s.pop();
                    }
                }
            }
        }
        if(s.empty()) {
            cout << "yes\n";
        }
        else{
            cout << "no\n";
        }
 
        while(!s.empty()){
            s.pop();
        }
        getline(cin, input);
    }
}

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U28gd2hlbiBJIGRpZSAodGhlIFtmaXJzdF0gSSB3aWxsIHNlZSBpbiAoaGVhdmVuKSBpcyBhIHNjb3JlIGxpc3QpLgpbIGZpcnN0IGluIF0gKCBmaXJzdCBvdXQgKS4KSGFsZiBNb29uIHRvbmlnaHQgKEF0IGxlYXN0IGl0IGlzIGJldHRlciB0aGFuIG5vIE1vb24gYXQgYWxsXS4KQSByb3BlIG1heSBmb3JtICkoIGEgdHJhaWwgaW4gYSBtYXplLgpIZWxwKCBJW20gYmVpbmcgaGVsZCBwcmlzb25lciBpbiBhIGZvcnR1bmUgY29va2llIGZhY3RvcnkpXS4KKFsgKChbKCBbIF0gKSAoICkgKCggKSldICkpIF0pLgogLgou

So when I die (the [first] I will see in (heaven) is a score list).
[ first in ] ( first out ).
Half Moon tonight (At least it is better than no Moon at all].
A rope may form )( a trail in a maze.
Help( I[m being held prisoner in a fortune cookie factory)].
([ (([( [ ] ) ( ) (( ))] )) ]).
 .
.