#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  string s;
  cin >> s;
  int c = 0;
  for (int i = 0; i < n - 1; i += 2) {
    if ((s[i] == 'a' and s[i + 1] == 'b') or
        (s[i] == 'b' and s[i + 1] == 'a')) {
      continue;
    } else {
      if (s[i] == 'a') {
        s[i + 1] = 'b';
        c++;
      } else {
        s[i + 1] = 'a';
        c++;
      }
    }
  }
  cout << c << endl << s << endl;
  return 0;
}
