#include <bits/stdc++.h>
int main() {
  int length, i, counta = 0, countb = 0, count = 0;
  scanf(" %d", &length);
  char string[length];
  scanf(" %s", string);
  i = 0;
  while (string[i] != '\0') {
    if (string[i] == 'a')
      counta++;
    else
      countb++;
    if ((i + 1) % 2 == 0) {
      if (counta != countb) {
        count++;
        if (counta > countb) {
          counta--;
          countb++;
          string[i] = 'b';
        } else {
          countb--;
          counta++;
          string[i] = 'a';
        }
      }
    }
    i++;
  }
  printf("%d\n", count);
  i = 0;
  while (string[i] != '\0') {
    printf("%c", string[i]);
    i++;
  }
  return 0;
}
