#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define Stackmax 100
#define Stackincrement 10
#define TRUE 1
#define  FALSE 0
typedef struct node
{
    char *base;
    char *top;
    int stacksize;
} sqstack;
void initstack(sqstack *s)
{
    s->base=s->top=(char *)malloc(sizeof(char)*Stackmax);
    if(!s->base) exit(-1);
    s->stacksize=Stackmax;
}
void push(sqstack *s,char e)
{
    /*if(s->top-s->base>=s->stacksize)//棧溢位
    {
        s->base=(char *)realloc(s->base,sizeof(char)*(s->stacksize+Stackincrement));
        if(!s->base) exit(-1);
        s->top=s->base+s->stacksize;
        s->stacksize+=Stackincrement;
    }
    */
    *(s->top)=e;
    s->top++;
}
char getpop(sqstack *s)//獲取棧頂值
{
    char x;
    if(s->top!=s->base)  x=*(s->top-1);
    return x;

}
void pop(sqstack *s)
{
    if(s->top!=s->base)
        s->top--;
}

int isempty(sqstack *s)
{
    if(s->top==s->base)
        return TRUE;//true 字型變藍，是因為本來就有其的存在？？？
    else return FALSE;
}
int main()
{
    sqstack s;
    char a[101];
    int i;
    int f;
    int len;
    while(gets(a))
    {
        len=strlen(a);
        f=1;
        initstack(&s);//忘記了！！！
        for(i=0; i<=len-1; i++)
        {
            if(a[i]=='('||a[i]=='{'||a[i]=='[')//右括號入棧
                push(&s,a[i]);

            else if(a[i]==')')//()
            {

                if(isempty(&s))//表示右括號多餘 空
                {
                    f=0;
                    break;
                }
                else
                {
                    if(getpop(&s)!='(')//
                    {
                        f=0;
                        break;
                    }
                    else pop(&s);

                }


            }
            else if(a[i]=='}')//{}
            {

                if(isempty(&s))// 空 左括號多餘
                {
                    f=0;
                    break;
                }
                else
                {
                    if(getpop(&s)!='{')//
                    {
                        f=0;
                        break;
                    }
                    else pop(&s);

                }


            }
            else if(a[i]==']')//[]
            {

                if(isempty(&s))
                {
                    f=0;
                    break;
                }
                else
                {
                    if(getpop(&s)!='[')
                    {
                        f=0;
                        break;
                    }
                    else pop(&s);

                }


            }


        }
        if(f==1&&isempty(&s))//都匹配成功，即最後棧為空的
            printf("yes\n");
        else printf("no\n");

    }





    return 0;
}