#include <bits/stdc++.h>
using namespace std;
int n;
string str;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> str;
  int ans = 0;
  for (int i = 0; i < n; i += 2) {
    int cnt = 0;
    if (str[i] == 'a')
      cnt++;
    else
      cnt--;
    if (str[i + 1] == 'a')
      cnt++;
    else
      cnt--;
    if (cnt != 0) {
      if (str[i] == 'a')
        str[i] = 'b';
      else
        str[i] = 'a';
      ans++;
    }
  }
  cout << ans << '\n';
  cout << str << '\n';
  return 0;
}
