#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  string s;
  cin >> n >> s;
  int o = 0, e = 0, cnt = 0;
  for (int i = 0; i < n; ++i) {
    if (s[i] == 'a')
      o++;
    else
      e++;
    if (i & 1) {
      if (o > e) {
        cnt++;
        if (s[i] == 'a') {
          s[i] = 'b';
        } else {
          s[i - 1] = 'b';
        }
        o--;
        e++;
      } else if (e > o) {
        cnt++;
        e--;
        o++;
        if (s[i] == 'b')
          s[i] = 'a';
        else
          s[i - 1] = 'a';
      }
    }
  }
  cout << cnt << '\n';
  cout << s;
  return 0;
}
