桃7

import java.util.Scanner;public class Tao7 {public static void main(String[] args) {// TODO Auto-generated method stubScanner sc = new Scanner(System.in);int tao = sc.nextInt();tao7(tao);}private static void tao7(int tao) { if(tao <= 0) return; // 笨方法 O(n) int num=0; for(int i=1; i<=tao; i++){ if(i%7 == 0) num++; else{ char[] s = Integer.toString(i).toCharArray(); for(int j=0; j<s.length; j++){ if(s[j] == '7'){ num++; break; }  } } }System.out.println(num);}}