#include 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)) //------------------------------------------------------- int N; string S; ll p10[101010]; ll num[101010]; ll sum[101010]; ll mo; ll gogo(deque& D,int first=0) { int i,j,k,l,r,x,y; if(D.size()<=4) { int v=0,x=0; FORR(c,D) v=v*10+c; for(i=first;i<=v;i++) { char buf[10]; string a,b; if(first) { sprintf(buf,"%d",i); a=buf; } else { sprintf(buf,"%06d",i); a=buf; a=a.substr(a.size()-D.size()); } b=a; reverse(ALL(b)); if(a==b) x++; } return x; } ll ret=0; if(first) { ret += 9*sum[D.size()-1]; (ret += (D[0]-1)*10*num[D.size()-2])%=mo; } else { (ret += D[0]*10*num[D.size()-2])%=mo; } int del=D[0]>D.back(); D.pop_front(); D.pop_back(); for(i=D.size()-1;i>=0&&del;i--) { D[i]--; if(D[i]>=0) del=0; else D[i]=9; } if(del==0) ret += gogo(D); return ret%mo; } ll hoge() { int i,j,k,l,r,x,y; string s; p10[0]=1; FOR(i,100001) { p10[i+1]=p10[i]*10%mo; if(i==0) num[i]=0; else num[i]=p10[(i-1)/2]%mo; sum[i]=((i==0)?0:sum[i-1])+num[i]; } deque T; FORR(c,S) T.push_back(c-'0'); return gogo(T,1); } void solve() { int i,j,k,l,r,x,y; string s; cin>>S; N=S.size(); mo=1000000000; cout<