#include <bits/stdc++.h>
using namespace std;
int main() {
	int n; cin >> n;
	string s; cin >> s;
	int ans = 0;
	string st = "";
	for(int i = 1; i < s.size(); i += 2) {
		int ans1 = (s[i - 1] != 'a') + (s[i] != 'b');
		int ans2 = (s[i - 1] != 'b') + (s[i] != 'a');
		if(ans1 < ans2) ans += ans1, st += "ab";
		else ans += ans2, st += "ba";
	}
	cout << ans << endl << st;
	return 0; 
} 

#include <bits/stdc++.h>
using namespace std;

int n;
int main() {
	cin >> n;
	vector < pair < int , int > > v(n);
	for(int i = 0; i < n; i++) cin >> v[i].first, v[i].second = i + 1;
	sort(v.begin(), v.end());
	long long cst = 0, al = 0;
	for(int i = n - 1; i >= 0; i--) {
		cst += al * v[i].first + 1;
		al++;
	}
	cout << cst << endl;
	for(int i = n - 1; i >= 0; i--) cout << v[i].second << " ";
	return 0; 
} 

#include <bits/stdc++.h>
using namespace std;
const int N = 10, n = 6;
pair <int, int> a[N];

const double dx[8] = {1, -0.5, 0, 0, 0.5, -0.5, 0.5, -0.5};
const double  dy[8] = {0, 0, 0.5, -0.5, 0.5, 0.5, -0.5, -0.5};

bool cov(double x, double y, double aa, double bb, double cc, double dd) {
	return aa <= x && x <= cc && bb <= y && y <= dd; 
}
int main() {
	for(int i = 1; i <= n; i++) cin >> a[i].first >> a[i].second;
	for(int i = 0; i < n; i++) {
		for(int j = 0; j < n; j++) {
			int x = a[i].first, y = a[j].second;
			for(int d = 0; d < 8; d++) {
				double fx = x + dx[d], fy = y + dy[d];
				if(cov(fx, fy, a[1].first, a[1].second, a[2].first, a[2].second)
			 && !cov(fx, fy, a[3].first, a[3].second, a[4].first, a[4].second)
			 && !cov(fx, fy, a[5].first, a[5].second, a[6].first, a[6].second)) {
					cout << "YES\n";
					return 0;
				}
			}
		}
	}
	cout << "NO\n";
	return 0; 
} 

#include <bits/stdc++.h>
typedef long long ll;
using namespace std;

const int N = 200000 + 10;
int n, a[N];
int main(){
	cin >> n;
	int now = 0;
	for(int i = 1; i <= n; i++) {
		cin >> a[i];
		if(i > 1) now = __gcd(now, abs(a[i] - a[i - 1]));
	}
	int mx = *max_element(a + 1, a + n + 1);
	long long ans = 0;
	for(int i = 1; i <= n; i++) {
		ans += 1LL * (mx - a[i]) / now;
	}
	cout << ans << " " << now << endl;
	return 0; 
}

#include <bits/stdc++.h>
using namespace std;
// 1,1,2,1,2,3,1,2,3,4,1,2,3,4,5,

int num(int x) {
	int cntt = 0;
	while(x) cntt ++, x /= 10;
	return cntt;
}

long long n;


long long pow(int x, int t) {
	long long res = 1;
	while(t--) res *= x;
	return res;
}
long long check2(int x) {
	int d = num(x);
	return 1LL * (x + 1) * d - 1LL * ((pow(10, d) - 1) / 9);
}

long long check1(int x) {
	if(x == 0) return 0; 
	
	for(int dg = 0; dg <= 9; dg++) {
		long long bd1 = pow(10, dg), bd2 = pow(10, dg + 1) - 1;
		if(bd1 <= x && x <= bd2) return check1(bd1 - 1) + 1LL * (check2(bd1) + check2(x)) * (x - bd1 + 1) / 2;
	}
}
int main() {
	int q; cin >> q;
	while(q--) {
		cin >> n;
		if(n == 1) {
			puts("1");
			continue;
		}
		int l = 1, r = 1000000000, ans = 0;
		while(l <= r) {
			int mid = (l + r) >> 1;
			long long ans1 = check1(mid);
			if(ans1 >= n) ans = mid, r = mid - 1;
			else l = mid + 1;
		}
		ans--;
		long long ft = check1(ans);
		ans++;
		l = 1, r = ans;
		ans = 0;
		while(l <= r) {
			int mid = (l + r) >> 1;
			long long ans1 = check2(mid);
			if(ft + ans1 >= n) ans = mid, r = mid - 1;
			else l = mid + 1;
		}
		
		if(ans == 1) {
			puts("1");
			continue;
		}
		ans--;
		long long final = ft + check2(ans);
		string s = ""; ans++;
		long long cop = ans;
		while(cop) s.push_back(cop % 10 + '0'), cop /= 10;
		reverse(s.begin(), s.end());
		cout << s[n - final - 1] << endl;
	}
	return 0; 
} 

Let $$$DP(i) = $$$ The minimum cost we need to connect all room in $$$[1, i]$$$ to internet. First there have $$$DP(i) = DP(i - 1) + i$$$. For each j between $$$[i-k, i]$$$, if $$$s[j] = '1'$$$, we can update $$$DP(i)$$$ using $$$DP(j - k) + j$$$.

#include <bits/stdc++.h>
#define ls(p) ((p) << 1)
#define rs(p) ((p) << 1 | 1)
using namespace std;
typedef long long ll;
const int N = 200000 + 5;
int n, k;
char s[N];
ll dp[N];

struct seg {
ll mx[N << 2];
seg() {
	memset(mx, 0x3f, sizeof(mx));
}
void upd(int p, int l, int r, int v, ll c) {
	if(l == r) {mx[p] = c; return ;}
	int mid = (l + r) >> 1;
	v <= mid ? upd(ls(p), l, mid, v, c) : upd(rs(p), mid + 1, r, v, c);
	mx[p] = min(mx[ls(p)], mx[rs(p)]);
}
long long qry(int p, int l, int r, int ql, int qr) {
	if(ql <= l && r <= qr) return mx[p];
	int mid = (l + r) >> 1;
	long long res = 0x3f3f3f3f3f3f3f3fll;
	if(ql <= mid) res = min(res, qry(ls(p), l, mid, ql, qr));
	if(qr > mid) res = min(res, qry(rs(p), mid + 1, r, ql, qr));
	return res;
}
}t1, t2;
int main() {
	cin >> n >> k >> (s + 1);
	dp[0] = 0;
	t2.upd(1, 0, n, 0, 0);
	for(int i = 1; i <= n; i++) {
		dp[i] = dp[i - 1] + i;
		if(s[i] == '1') dp[i] = min(dp[i], dp[max(i - k - 1, 0)] + i);
		if(max(i - k, 1) <= max(i - 1, 1) && max(i - 1, 1) < i)
			dp[i] = min(dp[i], t1.qry(1, 1, n, max(i - k, 1), max(i - 1, 1)));
		if(s[i] == '1') {
			t1.upd(1, 1, n, i, t2.qry(1, 0, n, max(i - k - 1, 0), max(i - 1, 0)) + i);
		}
		else t1.upd(1, 1, n, i, 0x3f3f3f3f3f3f3f3fll);
		t2.upd(1, 0, n, i, dp[i]);
	}
	
	cout << dp[n] << endl;
	return 0; 
}