#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int TESTS = 1;
  while (TESTS--) {
    long long n;
    cin >> n;
    long long ans = 0;
    string s;
    for (long long i = 0; i < n / 2; i++) {
      char c1, c2;
      cin >> c1 >> c2;
      if (c1 != c2) {
        s.push_back(c1);
        s.push_back(c2);
      } else
        ans++, s.push_back('a'), s.push_back('b');
    }
    cout << ans << '\n' << s;
  }
  return 0;
}
