#include <bits/stdc++.h>
using namespace std;
const int ten5 = 1e5;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  char s[n];
  int a = 0, b = 0, k = 0;
  for (auto i = 0; i < n; i++) {
    cin >> s[i];
    if (s[i] == 'a')
      a++;
    else
      b++;
    if (i % 2 == 1) {
      if (a != b) {
        k++;
        if (a > b) {
          s[i] = 'b';
          a = b;
        } else {
          s[i] = 'a';
          b = a;
        }
      }
    }
  }
  cout << k << '\n';
  for (auto i = 0; i < n; i++) cout << s[i];
  return 0;
}
