#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e5 + 5;
const double eps = 1e-8;
int cnt[5];
int n;
string s;
int main() {
  cin >> n;
  cin >> s;
  int ans = 0;
  memset(cnt, 0, sizeof cnt);
  for (int i = 0; i < n; ++i) {
    cnt[s[i] - 'a']++;
    if (i & 1) {
      if (cnt[1] != cnt[0]) {
        ans++;
        if (s[i] == 'b') {
          s[i] = 'a';
          cnt[0]++;
          cnt[1]--;
        } else {
          s[i] = 'b';
          cnt[0]--;
          cnt[1]++;
        }
      }
    }
  }
  cout << ans << endl;
  cout << s << endl;
}
