#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
constexpr int INF = 1e9;
constexpr long long LINF = 1e17;
constexpr int MOD = 1000000007;
constexpr double PI = 3.14159265358979323846;
vector<ll> ans;
ll n;

void dfs(int i,ll now){
    ans.push_back(now);
    if(i==9) return;
    else{
        dfs(i+1,now*10);
        dfs(i+1,now*10+3);
        dfs(i+1,now*10+6);
        dfs(i+1,now*10+9);
    }
}

int main(){
    cin >> n;
    for(int i=12;i<100;i+=3){
        ans.push_back(i);
    }
    dfs(0,0);
    sort(ans.begin(),ans.end());
    ans.erase(unique(ans.begin(),ans.end()),ans.end());
    ll res = 0;
    rep(i,ans.size()){
        if(ans[i]<10||ans[i]>n) continue;
        else ++res;
    }
    cout << res << endl;

    return 0;
}