import std.stdio, std.string, std.conv, std.algorithm, std.numeric;
import std.range, std.array, std.math, std.typecons, std.container, core.bitop;


void main() {
    while (1) {
        auto s = readln.chomp;

        if (s == ".") return;

        writeln(isBalance(s) ? "yes" : "no");
    }
}

bool isBalance(string s) {
    auto st = Stack!(char)(200);

    foreach (ch ; s) {
        if (ch == '(' || ch == '[') st.push(ch);
        else if (ch == ')') {
            if (st.empty || st.top != '(') return false;
            else st.pop;
        }
        else if (ch == ']') {
            if (st.empty || st.top != '[') return false;
            else st.pop;
        }
    }

    return st.empty;
}

struct Stack(T) {
private:
    int N, peek;
    T[] data;

public:
    this(int size) 
    {
        N = size;
        data = new T[](N);
    }

    bool empty() @property
    {
        return peek == 0;
    }

    bool full() @property
    {
        return peek == N;
    }

    void push(T x) @property
    {
        assert(!full);
        data[peek++] = x;
    }

    void pop() @property
    {
        assert(!empty);
        --peek;
    }

    T top() @property
    {
        return data[peek - 1];
    }

    void clear() @property
    {
        peek = 0;
    }

    int length() @property
    {
        return peek;
    }

}

void scan(T...)(ref T args) {
    string[] line = readln.split;
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}


void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}