#include using namespace std; //#include //using namespace atcoder; using ll = long long; using vll = vector; using vvll = vector; using vvvll = vector; using vvvvll = vector; using vvvvvll = vector; using vvvvvvll = vector; using vb = vector; using vvb = vector; using vvvb = vector; using vvvvb = vector; using vd = vector; using vvd = vector; using vvvd = vector; using vvvvd = vector; using vvvvvd = vector; #define all(A) A.begin(),A.end() #define ALL(A) A.begin(),A.end() #define rep(i, n) for (ll i = 0; i < (ll) (n); i++) using pqr = priority_queue, vector>, greater>>; #define tN(t) (t==1?XN:YN) #define tS(t) (t==1?XS:YS) #define tA(t) (t==1?XA:YA) template bool chmax(T& p, T q, bool C = 1) { if (C == 0 && p == q) { return 1; } if (p < q) { p = q; return 1; } else { return 0; } } template bool chmin(T& p, T q, bool C = 1) { if (C == 0 && p == q) { return 1; } if (p > q) { p = q; return 1; } else { return 0; } } ll gcd(ll(a), ll(b)) { if (b == 0)return a; ll c = a; while (a % b != 0) { c = a % b; a = b; b = c; } return b; } ll sqrtz(ll N) { ll L = 0; ll R = sqrt(N) + 10000; while (abs(R - L) > 1) { ll mid = (R + L) / 2; if (mid * mid <= N)L = mid; else R = mid; } return L; } void d(vb &AB, string &A, string &B) { rep(i, A.size()) { bool OK = 1; for (ll j = 0; j < B.size(); j++) { if (i + j >= A.size())break; if (A[i + j] == '?' || B[j] == '?')continue; if (A[i + j] != B[j])OK = 0; } AB[i] = OK; } } ll res = 1e18; void f(string &A, string &B, string &C, vb &AB, vb &BC, vb &AC) { rep(i, A.size() + 1) { if (!AB[i])continue; rep(j, A.size() + B.size() + 2) { if (!BC[j])continue; if (!AC[i + j])continue; ll L=ll(max({ll(i+j+C.size()),ll(i+B.size()),ll(A.size())})); chmin(res, L); } } return; } const ll mod = 998244353; int main() { cin.tie(nullptr); ios::sync_with_stdio(false); ll N; cin>>N; ll an=0; for(ll i=1;i<=1e5;i++){ string S=to_string(i); S=S+S+S; ll M=stoll(S); an+=(M<=N); } cout<