1 #include<bits/stdc++.h>
2 #define numm ch-48
3 #define pd putchar(' ')
4 #define pn putchar('
')
5 #define pb push_back
6 #define mp make_pair
7 #define fi first
8 #define se second
9 #define fi first
10 #define se second
11 #define fre1 freopen("1.txt","r",stdin)
12 #define fre2 freopen("2.txt","w",stdout)
13 using namespace std;
14 template <typename T>
15 void read(T &res) {
16 bool flag=false;char ch;
17 while(!isdigit(ch=getchar())) (ch=='-')&&(flag=true);
18 for(res=numm;isdigit(ch=getchar());res=(res<<1)+(res<<3)+numm);
19 flag&&(res=-res);
20 }
21 template <typename T>
22 void write(T x) {
23 if(x<0) putchar('-'),x=-x;
24 if(x>9) write(x/10);
25 putchar(x%10+'0');
26 }
27 const int maxn=100010;
28 typedef long long ll;
29 typedef long double ld;
30 const ll mod=1e9+7;
31 const int inf=0x3f3f3f3f;
32 ll cnt[3];
33 ///记录从1-i前缀和(mod 3)为1,2,3的出现次数
34 char s[maxn];
35 int main()
36 {
37 scanf("%s",s);
38 int len=strlen(s);
39 cnt[0]=1;///一开始，前缀和为0，所以cnt[1]=1;
40 cnt[1]=cnt[2]=0;
41 ll sum=0LL,ans=0LL;
42 for(int i=0;i<len;i++) {
43 sum=(sum+(s[i]-48))%3;
44 if(i>=1&&s[i]==48&&s[i-1]==48)
45 ///个位十位00，从i到0找前缀和与当前相同（说明这段区间的数mod3都为0）的数
46 ///把个数加起来
47 ans+=cnt[sum];
48 else if(s[i]==48) ans++;
49 cnt[sum]++;
50 }
51 write(ans);pn;
52 return 0;
53 }
