#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  map<char, int> mp;
  char a = 'a';
  char b = 'b';
  int cng = 0;
  for (int i = 0; i < n; i++) {
    mp[s[i]]++;
    if (i & 1) {
      if (mp[a] != mp[b]) {
        cng++;
        if (s[i] == 'a') {
          s[i] = 'b';
          mp[b]++;
          mp[a]--;
        } else {
          s[i] = 'a';
          mp[a]++;
          mp[b]--;
        }
      }
    }
  }
  cout << cng << endl;
  cout << s;
}
