#include <bits/stdc++.h>
using namespace std;
int x4[] = {0, 0, 1, -1};
int y4[] = {1, -1, 0, 0};
int main() {
  ios_base::sync_with_stdio(false), cin.tie(nullptr);
  int n;
  cin >> n;
  string x;
  cin >> x;
  int a = 0, b = 0;
  int counter = 0;
  for (int i = 1; i <= n; ++i) {
    if (!((i)&1)) {
      if (x[i - 1] == 'a') {
        if (a + 1 == b) {
          a++;
        } else {
          counter++;
          x[i - 1] = 'b';
          b++;
        }
      } else {
        if (b + 1 == a) {
          b++;
        } else {
          counter++;
          a++;
          x[i - 1] = 'a';
        }
      }
    } else if (x[i - 1] == 'a') {
      a++;
    } else {
      b++;
    }
  }
  cout << counter << "\n";
  cout << x << "\n";
  return 0;
}
