#include <bits/stdc++.h>

#define F first
#define S second
#define MP make_pair
#define pb push_back
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define LCM(a, b) (a) / __gcd((a), (b)) * (b)
#define CEIL(a, b) (a)/(b)+(((a)%(b))?1:0)
#define log_2(a) (log((a)) / log(2))
#define ln '\n'

using namespace std;
using LL = long long;
using ldouble = long double;
using P = pair<int, int>;
using LP = pair<LL, LL>;

static const int INF = INT_MAX;
static const LL LINF = LLONG_MAX;
static const int MIN = INT_MIN;
static const LL LMIN = LLONG_MIN;
static const int MOD = 1e9 + 7;
static const int SIZE = 200005;

const int dx[] = {0, -1, 1, 0};
const int dy[] = {-1, 0, 0, 1};

vector<LL> Div(LL n) {
    vector<LL> ret;
    for(LL i = 1; i * i <= n; ++i) {
        if(n % i == 0) {
            ret.pb(i);
            if(i * i != n) ret.pb(n / i);
        }
    }
    sort(all(ret));
    return ret;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    string s;
    cin >> s;

    int res = ((s[0] - '0') * 10 + s[1] - '0') / 3;
    if(s.size() <= 2) {
        cout << res - 3 << endl;
        return 0;
    }

    int tmp = 0;
    int dp[10][10][2] = {};
    for(int i = 0; i < s.size() - 2; ++i) {
        int c = s[i] - '0';
        if(i == 0) {
            if(c % 3 == 0) {
                dp[0][c][1] = 1;
            }
            for(int j = 0; j < c; ++j) {
                if(j % 3 == 0) dp[0][j][0] = 1;
            }
        } else {
            if(c % 3 == 0) {
              for(int j = 0; j <= 9; ++j) {
                    dp[i][c][1] += dp[i - 1][j][1];
                }
            }

            for(int j = 0; j <= 9; ++j) {
                if(j % 3 != 0) continue;
                for(int k = 0; k <= 9; ++k) {
                    dp[i][j][0] += dp[i - 1][k][0];
                }

                for(int k = 0; k < c; ++k) {
                    dp[i][j][0] += dp[i - 1][k][1];
                }
            }
        }
    }

    for(int i = 0; i <= 9; ++i) {
        tmp += dp[int(s.size()) - 2 - 1][i][0];
    }
    tmp--;

    int cnt = 4;
    int ccnt = 0;
    for(int i = 10; i < 100; ++i) {
        int t = i;
        bool f = true;
        while(t > 0) {
            if(t % 10 % 3 != 0) {
                f = false;
                break;
            }
            t /= 10;
        }
        if(f) ++cnt;
        if(i % 3 == 0) ++ccnt;
    }

    res = tmp * cnt + ccnt;
    bool flg = false;
    for(int i = 0; i <= 9; ++i) {
        flg = (flg || dp[int(s.size()) - 2 - 1][i][1] != 0);
    }

    if(flg && (s[s.size() - 2] - '0') % 3 == 0 && (s[s.size() - 1] - '0') % 3 == 0) {
        tmp = (s[s.size() - 2] - '0') * 10 + s[s.size() - 1] - '0';
        for(int i = 0; i <= tmp; i += 3) {
            if(i <= 9) ++res;
            else {
                if(i % 10 % 3 == 0 && i / 10 % 3 == 0) ++res;
            }
        }
    }
    cout << res << endl;
    return 0;
}