#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef pair<int,int> P;
int INF = 1e16+7;
int mod = 998244353;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
signed main() {
    int N;
    cin >> N;
    int cnt = 0;
    for(int i = 10; i <= min(99LL,N); i++) {
        if((i/10+i%10)%3 == 0 && i%3 == 0) {
            cnt++;
        }
    }
    string S = to_string(N);
    for(int i = 2; i < S.size()-1; i++) {
        cnt += 3*pow(4,i);
    }
    if(S.size() >= 3) {
        cnt += ((S[0]-'0')-1)/3*pow(4,S.size()-1);
    }
    if((S[0]-'0')%3 == 0 && S.size() >= 3) {
        for(int i = 1; i < S.size(); i++) {
            if(S[i]-'0' >= 1 && i+1 != S.size()) {
                cnt += (S[i]-'0'-1)/3*pow(4,S.size()-i-1);
            }
            if(i+1 == S.size()) {
                cnt += 1+(S[i]-'0')/3;
            }
            if((S[i]-'0')%3) {
                break;
            }
        }
    }
    cout << cnt << endl;
}