#include <bits/stdc++.h>
using namespace std;
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cerr << name << " : " << arg1 << "\n";
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << " : " << arg1 << " , ";
  __f(comma + 1, args...);
}
inline long long int gcd(long long int a, long long int b) {
  a = abs(a), b = abs(b);
  while (b) a = a % b, swap(a, b);
  return a;
}
inline long long int power(long long int a, long long int p) {
  long long int res = 1, x = a;
  while (p) {
    if (p & 1) res = (res * x);
    x = (x * x), p >>= 1;
  }
  return res;
}
inline long long int big_mod(long long int a, long long int p,
                             long long int m) {
  long long int res = 1 % m, x = a % m;
  while (p) {
    if (p & 1) res = (res * x) % m;
    x = (x * x) % m, p >>= 1;
  }
  return res;
}
const int INF = 1e9;
int main() {
  string ans = "";
  int cnt = 0;
  int n;
  cin >> n;
  string s;
  cin >> s;
  for (int i = 0; i < n; i += 2) {
    if (s[i] == 'a' && s[i + 1] == 'b' || s[i] == 'b' && s[i + 1] == 'a') {
      ans += s[i];
      ans += s[i + 1];
    } else {
      cnt++;
      if (s[i] == 'a') {
        ans += "b";
        ans += "a";
      } else {
        ans += "a";
        ans += "b";
      }
    }
  }
  cout << cnt << endl;
  cout << ans << endl;
  return 0;
}
