#include <bits/stdc++.h>
using namespace std;
long long n;
string s;
long long cnt = 0;
long long aa = 0, bb = 0;
void input() {
  cin >> n >> s;
  return;
}
void solve() {
  for (long long i = 0; i < n; i++) {
    if (s[i] == 'a') {
      aa++;
    } else {
      bb++;
    }
    if (i % 2 == 1 && aa != bb) {
      cnt++;
      if (s[i] == 'a') {
        s[i] = 'b';
      } else {
        s[i] = 'a';
      }
      aa = bb = (aa + bb) / 2;
    }
  }
  cout << cnt << "\n" << s;
  return;
}
void output() { return; }
signed main() {
  ios_base::sync_with_stdio(false);
  input();
  solve();
  output();
  return 0;
}
