#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10;
char str[N];
int main() {
  int len = 0;
  scanf("%d%s", &len, str + 1);
  int na = 0, nb = 0, ans = 0;
  for (int i = 1; i <= len; i++) {
    if (str[i] == 'a')
      na++;
    else
      nb++;
    if (i % 2 == 0) {
      if (na > nb) {
        str[i] = 'b';
        na--;
        nb++;
        ans++;
      } else if (nb > na) {
        str[i] = 'a';
        nb--;
        na++;
        ans++;
      }
    }
  }
  printf("%d\n%s", ans, str + 1);
}
