#include <iostream>
#include <string>

using namespace std;

int main ()
{
    string s;

    cout << "The string is: " << endl;
    cin >> s;

    string::size_type pos = 0;
    do {
        pos = s.find('a', pos);
        if (pos == string::npos) break;
        s.insert(pos, "aa");
        // or: s.insert(pos, 2, 'a');
        pos += 3;
    }
    while (true);

    cout << "The modified string is: " << endl;
    cout << s;
}