大佬帮忙看看问题在哪？输出有问题

import java.util.ArrayList;

import java.util.List;

import java.util.Scanner;

public static void main(String[] args) {

// TODO Auto-generated method stub

int count=0;

Scanner sc=new Scanner(System.in);

int n=Integer.parseInt(sc.nextLine());

for(Integer i=1;i<=n;i++){

String string=i.toString();

count=count+check(string);

}

System.out.println(count);

}

public static int check(String string){

int result=0;

List<Character> list=new ArrayList<>();

int count=0;

for(int i=0;i<string.length();i++){

list.add(string.charAt(i));

}

for (Character c : list) {

if (c.equals('4')||c.equals('7')) {

count=count+1;

}

}

if (count==list.size()) {

result=1;

}

return result;

}