#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
char s[100];
char a[100];
int main()
{
    int i,j,k,f,top,len;
    while(gets(s) != '\0')
    {
        len = strlen(s);
        top = 0;
        f = 0;
        for(i = 0; i < len; i ++)
        {
            if(s[i] == ')')
            {
                if(top == 0)
                {
                    f = 1;
                    break;
                }
                else
                {
                    if(a[top - 1] == '(')
                    {
                        top --;
                    }
                    else
                    {
                        f = 1;
                        break;
                    }
                }
            }
            else if(s[i] == '(')
            {
                a[top ++] = '(';
            }
            else  if(s[i] == '}')
            {
                if(top == 0)
                {
                    f = 1;
                    break;
                }
                else
                {
                    if(a[top - 1] == '{')
                    {
                        top --;
                    }
                    else
                    {
                        f = 1;
                        break;
                    }
                }
            }
            else if(s[i] == '{')
            {
                a[top ++] = '{';
            }
            else if(s[i] == ']')
            {
                if(top == 0)
                {
                    f = 1;
                    break;
                }
                else
                {
                    if(a[top - 1] == '[')
                    {
                        top --;
                    }
                    else
                    {
                        f = 1;
                        break;
                    }
                }
            }
            else if(s[i] == '[')
            {
                a[top ++] = '[';
            }
        }
        if(top != 0 || f == 1)
            printf("no\n");
        else
            printf("yes\n");
    }
    return 0;
}