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#include <bits/stdc++.h>
using namespace std;
bool check(int x) {
string s = to_string(x);
string copy_s(s.size(), s[0]);
return copy_s == s;
}
int main() {
int n;
cin >> n;
int ans = 0;
for (int i = 1; i <= n; i++) {
if (check(i)) ans++;
}
cout << ans << endl;
return 0;
}