#include <bits/stdc++.h>
using namespace std;

#define rep(i,n) for (int i=0;i<(n);i++)
#define rep2(i,a,b) for (int i=(a);i<(b);i++)
#define rrep(i,n) for (int i=(n)-1;i>=0;i--)
#define rrep2(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define all(a) (a).begin(),(a).end()

typedef long long ll;
typedef pair<int, int> P;

ll N;

bool is_palindrome(ll n) {
  string s1, s2;
  s1 = s2 = to_string(n);
  reverse(all(s2));
  return s1 == s2;
}

void solve() {
  ll p = (ll)1e9 + 1;
  ll count, n;
  cin >> N;
  for (count = 0, n = p; n <= N; n += p) {
    if (is_palindrome(n)) {
      count++;
    }
  }
  cout << count << endl;
}

int main() {
  solve();
  return 0;
}