#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn=100010;
const int hzy=10007;
const int inf=(1<<30)-1;
typedef long long ll;
char s[maxn];
int c[maxn];
int tot=0;
int vis[maxn];
int main()
{
    while(scanf("%s",s)==1){
    int n=strlen(s);
    memset(c,0,sizeof(c));
    memset(vis,0,sizeof(vis));
    tot=0;int ok=0;
    int flag=0;
    char last=s[0];
    c[++tot]=1;
    vis[last]=1;
    for(int i=1;i<n;i++)
    if(last!=s[i]&&!vis[s[i]])
    {
        tot++;
        c[tot]=1;
        vis[s[i]]=1;
        last=s[i];
    }else if(last==s[i]) {
        c[tot]++;
    }
    else if(vis[s[i]]) {
        flag=1;break;
    }
    if(tot!=3) flag=1;
    //printf("%d %d %d\n",c[1],c[2],c[3]);
    if(c[2]!=c[1]||c[2]!=c[3]||c[1]!=c[3])
    {
        flag=1;
    }
    if(!flag) puts("YES");
    else puts("NO");
    }    
    return 0;
}