#include<iostream>


using namespace std;

int main() {
    string s;
    s = "ong vang lon ton den nha ong nau choi";
    cout << s << endl;

    int len = s.length();
    int i;

    for (i=len-3; i>=0; i--)
        if (s.substr(i, 3) ==  "ong")
            s.replace(i, 3, "con ong ngoan");

    cout << s << endl;


}