#include<cstdio>
#include<queue>
#include<utility>
#include<cstring>
#include<stack>
#include<algorithm>
#include<cmath>
#include<iostream>
#include<map>
#define MAX_N 100001
#define INF_INT 2147483647
#define INF_LL 9223372036854775807
#define REP(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
typedef long long int ll;
typedef pair<ll,ll> P;
void init(int n);
int find(int n);
void unite(int x,int y);
bool same(int x, int y);
ll bpow(ll,ll,ll);
typedef vector<int> vec;
typedef vector<vec> mat;
mat mul(mat &A,mat &B);
mat pow(mat A,ll n);
int dx[4] = {1,0,0,-1};
int dy[4] = {0,1,-1,0};


bool cmp_P(const P &a,const P &b){
  return a.second < b.second;
}
int main()
{
  ll N,sin;
  cin >> N;
  sin = N / (1000000001);
  if(sin == 0){
    cout << 0 << endl;
    return 0;
  }
  vector<vector<ll> > kaibun(12,vector<ll>(0));
  vector<ll> kaib(0);
  for(int i=0;i<=9;i++){
    kaibun[1].push_back(i);
    kaib.push_back(i);
  }
  for(int i=0;i<=9;i++){
    kaibun[2].push_back(i*11);
    kaib.push_back(i*11);
  }
  for(int i=3;i<=10;i++){
    for(int j=0;j<kaibun[i-2].size();j++){
      for(int k=1;k<=9;k++){
        kaibun[i].push_back(k*pow(10,i-1)+10*kaibun[i-2][j]+k);
        kaib.push_back(k*pow(10,i-1)+10*kaibun[i-2][j]+k);
        
      }
    }
    REP(k,kaibun[i-2].size()){
      kaibun[i].push_back(10*kaibun[i-2][k]);
    }
  }
  sort(kaib.begin(),kaib.end());
  kaib.erase(unique(kaib.begin(),kaib.end()),kaib.end());
  kaib.erase(kaib.begin());
  cout << upper_bound(kaib.begin(),kaib.end(),sin) - kaib.begin() << endl;
  return 0;
}