#include <bits/stdc++.h>
using namespace std;
long dp[12][2];
int main() {
	string S;
	cin >> S;
	const int N = S.size();
	long ans = 0;
	dp[0][0] = 1;
	for(int i = 0; i < N; i++) {
		for(int j = 0; j < 2; j++) {
			int lim = j ? 9 : S[i] - '0';
			for(int d: {0,3,6,9}) if(d <= lim) {
				dp[i + 1][j || d < S[i]-'0'] += dp[i][j];
			}
		}
	}

	long tmp = dp[N][0] + dp[N][1] - 4;
	for(int x = 10; x < 100 && x <= stoll(S); x++) {
		int t = (x % 10) + (x / 10);
		if (t % 3 == 0 and ((x /10) % 3 != 0)) {
			tmp++;
		}
	}
	cout << tmp << endl;
}