参考答案：

#include<iostream>
#include<string>
using namespace std;
string s;
int n;
int main()
{
    cin >> n;
    cin >> s;
    for (int i = 0; i < (int)s.size(); ++i)
    {
        if (s[i] != '5') cout << s[i];
        else cout << '*';
    }
    cout << endl;

    return 0;
}