AtCoder Beginner Contest 136(B - Uneven Numbers)

1. #include< bits/stdc++.h >
2. using namespace std;
3. int main(){
4. int n, ans = 0;
5. cin >> n;
6. for(int i = 1; i <= n; i++) {
7. string s;
8. stringstream ss;
9. ss << i;
10. ss >> s;
11. if(s.size()%2) ans++;
12. }
13. cout << ans << endl;
14. return 0;
15. }