题解 | #挑7#

import java.util.*;
import java.io.*;
public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String s=null;
        while((s=br.readLine())!=null){
            int n=Integer.valueOf(s);
            int count=0;
            for(int i=7;i<=n;i++){
                count=count+youqi(i);
            }
            System.out.println(count);
        }
    }
    public static int  youqi(int n){
        if(n%7==0) return 1;
        while(n>=7){
            if(n%10==7) return 1;
            n=n/10;
        }
        return 0;
    }
}