#include <bits/stdc++.h> using namespace std; typedef signed long long ll; #undef _P #define _P(...) (void)printf(__VA_ARGS__) #define FOR(x,to) for(x=0;x<(to);x++) #define FORR(x,arr) for(auto& x:arr) #define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++) #define ALL(a) (a.begin()),(a.end()) #define ZERO(a) memset(a,0,sizeof(a)) #define MINUS(a) memset(a,0xff,sizeof(a)) //------------------------------------------------------- ll N; ll p10[20]; string A; ll ret=0; void solve() { int i,j,k,l,r,x,y; string s; p10[0]=1; FOR(i,10) p10[i+1]=p10[i]+1; vector<string> V; for(i=1;i<=99999;i++) { char buf[1010]; string S,T; sprintf(buf,"%d",i); S=buf; T=S; reverse(ALL(T)); V.push_back(S+T); V.push_back(S+T.substr(1)); } sort(ALL(V)); V.erase(unique(ALL(V)),V.end()); cin>>A; string Z="000000000000000"; FORR(a,V) { if(a.size()>9) continue; string b = a+Z.substr(0,9-a.size())+a; if(b.size()<A.size() || (b.size()==A.size() && b<=A)) ret++; } cout<<ret<<endl; } int main(int argc,char** argv){ string s;int i; if(argc==1) ios::sync_with_stdio(false), cin.tie(0); FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin); solve(); return 0; }