#include <bits/stdc++.h>
using namespace std;
int count_a;
int count_b;
int ans;
int main() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  for (int i = 1; i < n; i += 2) {
    count_a = 0;
    count_b = 0;
    for (int j = i - 1; j <= i; ++j) {
      if (s[j] == 'a') {
        ++count_a;
      } else {
        ++count_b;
      }
    }
    if (count_a == count_b) {
      continue;
    } else if (count_a > count_b) {
      int check = count_a - count_b;
      check /= 2;
      int k = 0;
      for (int j = i - 1; i <= i; ++j) {
        if (s[j] == 'a') {
          s[j] = 'b';
          ++k;
          ++ans;
        }
        if (k == check) {
          break;
        }
      }
    } else if (count_b > count_a) {
      int check = count_b - count_a;
      check /= 2;
      int k = 0;
      for (int j = i - 1; i <= i; ++j) {
        if (s[j] == 'b') {
          s[j] = 'a';
          ++k;
          ++ans;
        }
        if (k == check) {
          break;
        }
      }
    }
  }
  cout << ans << endl;
  for (int i = 0; i < n; ++i) {
    cout << s[i];
  }
}
