题解 | #挑7#

import java.util.*;
import java.io.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        try {
            String s = br.readLine();
            //包含7或7的倍数
            int n = Integer.valueOf(s);
            int count = 0;
            for (int i = 1; i <= n; i++) {
                String s1 = String.valueOf(i);
                if (s1.contains("7")) {
                    count++;
                    continue;
                }
                if (i % 7 == 0) {
                    count++;
                }
            }
            System.out.println(count);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}