#include <string>
#include <vector>
using namespace std;
string solution(string phone_number) {
string answer = "";
for(int i=0; i< phone_number.size(); i++)
{
if(i<phone_number.size()-4)
{
answer += "*";
}
else
{
answer += phone_number[i];
}
}
return answer;
}
30초컷