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

#define FOR(i,l,r) for(int i = (int) (l);i < (int) (r);i++)
#define ALL(x) x.begin(),x.end()
template<typename T> bool chmax(T& a,const T& b){ return a < b ? (a = b,true) : false; }
template<typename T> bool chmin(T& a,const T& b){ return b < a ? (a = b,true) : false; }
typedef long long ll;

ll N;
const ll M = 1e9 + 1;

ll dfs(string s)
{
	ll res = 0;
	if(s.empty() == false && s.front() != '0' && stoll(s) >= 1 && stoll(s) <= N / M){
		res++;
	}
	if(s.size() < 9){
		for(char c = '0';c <= '9';c++){
			res += dfs(c + s + c);
		}
	}
	return res;
}

int main()
{
	scanf("%lld",&N);

	ll ans = dfs("");
	FOR(i,0,10){
		ans += dfs(to_string(i));
	}
	printf("%lld\n",ans);

	return 0;
}