#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string k;
  cin >> k;
  int y = 0;
  int u = 0;
  for (y = 0; y < n; y += 2) {
    if (k[y] == 'a' && k[y + 1] == 'b' || k[y] == 'b' && k[y + 1] == 'a') {
      continue;
    } else {
      char t = k[y];
      k[y + 1] = k[y] == 'a' ? 'b' : 'a';
      u++;
    }
  }
  cout << u << endl;
  cout << k << endl;
}
