성능을 위해 StringBuilder를 사용했습니다```{.java}
public class Main {
public static void main(String[] ar){
int cnt = 0;
StringBuilder s = new StringBuilder();
for(int i = 1; i <= 10000; i++){
s.append(i);
}
for(int i = 0; i < s.length(); i++){
if(s.charAt(i) == '8')
cnt++;
}
System.out.println(cnt);
}
}
```