#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  t = 1;
  while (t--) {
    int n;
    cin >> n;
    string s;
    cin >> s;
    int ca = 0, cb = 0, co = 0;
    int i = 0;
    while (i < n) {
      if (s[i] == 'a') {
        ca++;
      } else {
        cb++;
      }
      if (i & 1) {
        if (ca != cb) {
          co++;
          if (ca > cb) {
            s[i] = 'b';
            cb++;
            ca--;
          } else {
            ca++;
            cb--;
            s[i] = 'a';
          }
        }
      }
      i++;
    }
    cout << co << "\n" << s;
  }
}
