python/TangDou/LanQiaoBei/LanQiaoBei13ShengSai_ZJ_II/1.cpp

#include <bits/stdc++.h>

using namespace std;
int n, cnt;
int main() {
    cin >> n;
    for (int i = 3; i <= n; i++)
        if (i % 10 == 3) cnt++;

    cout << cnt << endl;
    return 0;
}