#include using namespace std; #define fi first #define se second #define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++) #define rep(i,n) repl(i,0,n) #define each(itr,v) for(auto itr:v) #define pb(s) push_back(s) #define mp(a,b) make_pair(a,b) #define all(x) (x).begin(),(x).end() #define dbg(x) cout<<#x"="<(x).count() typedef long long ll; typedef unsigned long long ull; typedef pair P; typedef pair PPI; typedef pair PL; typedef pair PPL; #define INF INT_MAX/3 #define MAX_N 1000 ll rec(ll n,ll nd,ll digit){ if(nd>digit/2+digit%2)return 1; ll res=1; ll maxd=(n/(ll)pow(10,digit-nd))%10; res*=nd==1?maxd:maxd+1; return res*rec(n,nd+1,digit); } ll n; ll res=0; int main(){ cin.sync_with_stdio(false); cin>>n; n/=1000000001; ll digit=1; for(ll x=1;x<=n;x*=10){ res+=rec(min(x*10-1,n),1LL,digit++); } cout<