cf 1216A

#include <bits\stdc++.h>

using namespace std;

int main()
{
    int n;
    cin >> n;
    string s;
    cin >> s;

    int c = 0, i;
    for(i = 0; i < n; i += 2)
    {
        if(s[i] == s[i+1]) c++;
    }

    printf("%d\n", c);
    for(i = 0; i < n; i += 2)
    {
        if(s[i] == s[i+1])
        {
            s[i] = 'a';
            s[i+1] = 'b';
        }
    }
    cout << s << endl;
}