#include "bits/stdc++.h"
using namespace std;
using ll=long long;
using ld=long double;
using vi=vector<int>;
using vvi=vector<vi>;
using vll=vector<ll>;
using vvll=vector<vll>;
using pii=pair<int,int>;
#define rep(i,n) for(int i=0;i<(n);i++)
#define sor(v) sort(v.begin(),v.end())
#define rev(v) reverse(v.begin(),v.end())
#define ALL(v) v.begin(),v.end()
#define pb push_back
template<class T>bool chmax(T &a, const T &b) {if (a<b) {a=b; return 1;} return 0;}
template<class T>bool chmin(T &a, const T &b) {if (b<a) {a=b; return 1;} return 0;}
template<class T>void printv(vector<T> v){ll n=v.size(); rep(i,n){cout<<v[i]; if(i==n-1)cout<<endl; else cout<<' ';}}
template<class T>void printvv(vector<vector<T>> v){for(auto V:v) printv(V);}
//constexpr int INF=1001001001;
//constexpr int mod=1e9+7;
//constexpr int mod=998244353;

int main(){
    int n; cin>>n;
    string s=to_string(n);
    int m=(int)s.length();
    vi dp(2);
    rep(j,m){
        vi nx(2);
        rep(b,2){
            int lim=b?(s[j]-'0'):9;
            for(int i=0;i<=lim;i+=3) nx[b&&i==lim]+=dp[b];
        }
        int lim=j?9:s[j]-'0';
        for(int i=3;i<=lim;i+=3) nx[j==0&&i==lim]++;
        swap(dp,nx);
    }
    int ans=dp[0]+dp[1]-3;
    //cout<<ans<<endl;
    int a[]={1,4,7},b[]={2,5,8};
    rep(i,3)rep(j,3){
        if(a[i]*10+b[j]<=n) ans++;
        if(b[j]*10+a[i]<=n) ans++;
    }
    cout<<ans<<endl;
}