#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if (y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if (x < y) x = y; }

int main() {
	vector<int> palins;
	reu(d, 1, 10)
		palins.push_back(d);
	for (int P = 1; P < (int)1e4; P *= 10) {
		reu(i, P, P * 10) {
			int revi = 0;
			for (int x = i, y = P; x > 0; x /= 10, y /= 10)
				revi += x % 10 * y;
			palins.push_back(i * P * 10 + revi);
			rep(d, 10) {
				palins.push_back(i * P * 100 + d * P * 10 + revi);
			}
		}
	}
	long long N;
	while (~scanf("%lld", &N)) {
		int ans = 0;
		for (ll x : palins) {
			ll y = ((ll)1e9 + 1) * x;
			if (y <= N) {
				++ ans;
			}
		}
		printf("%d\n", ans);
	}
	return 0;
}