#include <string>
#include <iostream>

using namespace std;

int main()
{

    string s1("12345"), s2;

    string::iterator it = s1.begin();

    s2 = s1;

    *it = '0';

    cout << "s1 = " << s1 << endl;
    cout << "s2 = " << s2 << endl;
}