#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, i, ans = 0;
  cin >> n;
  string s;
  cin >> s;
  for (i = 0; s[i]; i += 2) {
    if ((s[i] == 'a' && s[i + 1] == 'b') || (s[i] == 'b' && s[i + 1] == 'a'))
      continue;
    else {
      if (s[i] == 'a' && s[i + 1] == 'a')
        s[i + 1] = 'b', ans++;
      else
        s[i] = 'a', ans++;
    }
  }
  cout << ans << endl << s;
}
