#include <iostream>
#include <map>
#include <set>
#include <queue>
#include <cmath>
#include <vector>
#include <string>
#include <algorithm>
#include <functional>
using namespace std;
#pragma warning (disable: 4996)

long long N;

long long solve(long long pos, long long r) {
	if (r >= N) {
		if (100LL <= pos && pos <= N) { return 1; }
		return 0;
	}

	long long ret = 0;
	for (int i = 0; i <= 9; i += 3) {
		ret += solve(pos + 1LL * i * r, 10LL * r);
	}
	return ret;
}

int main() {
	cin >> N;
	long long r1 = solve(0, 1);
	long long r2 = 0;
	for (int i = 10; i <= 99; i++) {
		if (i <= N && i % 3 == 0 && ((i / 10) + (i % 10)) % 3 == 0) r2 += 1;
	}
	cout << r1 + r2 << endl;
	return 0;
}