#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n;
  string second;
  cin >> n >> second;
  long long ctr = 0, cnt = 0;
  for (long long i = 0; i < n; i++) {
    if (second[i] == 'a')
      ctr++;
    else
      ctr--;
    if (i % 2 && ctr) {
      cnt++;
      if (ctr < 0)
        second[i] = 'a';
      else
        second[i] = 'b';
      ctr = 0;
    }
  }
  cout << cnt << "\n";
  cout << second << "\n";
  return 0;
}
