Submission #6687075

---

Source Code Expand

#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <utility>
#include <algorithm>
#include <numeric>
#include <string>

using namespace std;
using ll = long long int;

#define rep(i, v) for(ll i = 0; i < (v); ++i)

int num(ll n){
    int i = 0;
    while(true){
        if(!n) break;
        i++;
        n /= 10;
    }
    return i;
}

int main(){
    ll N;
    cin >> N;

    ll count = 0;
    for(ll i = 0; i <= N; ++i){
        if(num(i) % 2 == 1) count++;
    }
    cout << count << endl;
}

Submission Info

Judge Result