#include<iostream>

using namespace std;

int main() {
    string s;
    s = "Xin chao Viet Nam";
    cout << s << endl;

    cout << "Do dai xau s la: " << s.length() << endl;
    int i;
    for (i=0; i<s.length(); i++)
        cout << s[i];
    cout << endl;

    s.erase(9, 5);
    cout << s << endl;

    s.insert(9, "Viet ");
    cout << s << endl;

    cout << s.substr(9, 4) << endl;

    cout << s.find("Viet") << endl;

    s.replace(9, 4, "deo Hai");

    cout << s << endl;


}