문자열문제

#include <string>
#include <vector>

using namespace std;

bool solution(string s) {
    bool answer = true;
    int check=0;
    check = s.length();
    if(check!=4&&check!=6)
    {
        answer = false;
    }
    else
    {
        for(int i=0;i<check;i++)
        {
            if(s.at(i)<48||s.at(i)>57)
            {
                answer = false;
                break;
            }
        }
    }
    return answer;
}