/**********************************************************************************/
/*  Problem: d124 "3的倍数" from                                               */
/*  Language: C (353 Bytes)                                                       */
/*  Result: AC(0ms, 268KB) judge by this@ZeroJudge                                */
/*  Author: kkmomo at 2013-05-08 22:59:36                                         */
/**********************************************************************************/


#include<stdio.h>

#define BUFFSIZE 10000

int main(void)
{
    int index, check;
    char buff[BUFFSIZE+1];
    check = 0;
    while(scanf("%s", buff)!=EOF)
    {
        index = buff[0]=='-' ? 1 : 0;
        for ( check = 0; buff[index]!='\0'; index++)
            check += buff[index];
        if (check%3!=0)
            printf("no\n");
        else
            printf("yes\n");
    }
    return 0;
}