#include <bits/stdc++.h>
using namespace std;
int main() {
  string a, b = "";
  int n, max1 = 0;
  cin >> n;
  cin >> a;
  for (int i = 0; i < n; i += 2) {
    if (!(a.substr(i, 2) == "ab" || a.substr(i, 2) == "ba")) {
      b += "ab";
      max1++;
    } else {
      b += a.substr(i, 2);
    }
  }
  cout << max1 << '\n' << b;
}
