#include "bits/stdc++.h"

using namespace std;

using ll = long long;
using ull = unsigned long long;

#define IOS ios::sync_with_stdio(0);cin.tie(0);
#define endl "\n"
#define rep(i, a, b) for(int i = (a); i < (b); ++i)


void solve() {
    int n;
    cin >> n;
    string s;
    cin >> s;
    vector<int> vis(n);
    vector<int> ans(n);
    auto is0 = [&](int i) {
        return !((s[i] - '0') ^ (vis[i] % 2));
    };
    rep(i, 0, n - 2) {
        if (is0(i)) {
            vis[i]++;
            vis[i + 1]++;
            vis[i + 2]++;
            ans[i + 1]++;
        }
    }
    int k = n / 3;
    int last2 = (1 - is0(n - 2)) * 2 + (1 - is0(n - 1));
    switch (n % 3) {
        case 0: {
            switch (last2) {
                case 0b00:
                case 0b01:
                case 0b10: {
                    cout << "0\n";
                    return;
                }
                case 0b11: {
                    rep(i, 0, n) {
                        ans[i]++;
                    }
                    break;
                }
            }
            break;
        }
        case 1: {
            switch (last2) {
                case 0b00: {
                    rep(i, 0, k) {
                        ans[3 * i + 2]++;
                    }
                    ans[n - 1]++;
                    break;
                }
                case 0b01: {
                    rep(i, 0, k) {
                        ans[3 * i]++;
                    }
                    break;
                }
                case 0b10: {
                    rep(i, 0, k) {
                        ans[3 * i + 1]++;
                    }
                    break;
                }
                case 0b11: {
                    rep(i, 0, n) {
                        ans[i]++;
                    }
                    break;
                }
            }
            break;
        }
        case 2: {
            switch (last2) {
                case 0b00: {
                    rep(i, 0, k) {
                        ans[3 * i + 1]++;
                    }
                    break;
                }
                case 0b01: {
                    rep(i, 0, k) {
                        ans[3 * i + 2]++;
                    }
                    ans[n - 1]++;
                    break;
                }
                case 0b10: {
                    rep(i, 0, k) {
                        ans[3 * i + 3]++;
                    }
                    ans[0]++;
                    break;
                }
                case 0b11: {
                    rep(i, 0, n) {
                        ans[i]++;
                    }
                    break;
                }
            }
            break;
        }
    }
    set<int> ans0, ans1, nans0;
    rep(i, 0, n) {
        if (!(ans[i] % 2)) {
            if (s[i] == '0') {
                ans0.emplace(i);
            } else {
                ans1.emplace(i);
            }
        } else {
            if (s[i] == '0') {
                nans0.emplace(i);
            }
        }
    }
    vector<int> ans_v;
    while (!ans0.empty() || !nans0.empty()) {
        if (ans0.empty()) {
            auto t = *nans0.begin();
            nans0.erase(nans0.begin());
            ans_v.emplace_back(t);
            ans1.emplace(t);
            if (auto i = ans1.find((t + n - 1) % n);i != ans1.end()) {
                ans0.emplace(*i);
                ans1.erase(i);
            } else if (i = nans0.find((t + n - 1) % n);i != nans0.end()) {
                nans0.erase(i);
            } else {
                nans0.emplace((t + n - 1) % n);
            }
            if (auto i = ans1.find((t + 1) % n);i != ans1.end()) {
                ans0.emplace(*i);
                ans1.erase(i);
            } else if (i = nans0.find((t + 1) % n);i != nans0.end()) {
                nans0.erase(i);
            } else {
                nans0.emplace((t + 1) % n);
            }
        } else {
            auto t = *ans0.begin();
            ans0.erase(ans0.begin());
            ans_v.emplace_back(t);
            if (auto i = ans0.find((t + n - 1) % n);i != ans0.end()) {
                ans1.emplace(*i);
                ans0.erase(i);
            } else if (i = ans1.find((t + n - 1) % n);i != ans1.end()) {
                ans0.emplace(*i);
                ans1.erase(i);
            } else if (i = nans0.find((t + n - 1) % n);i != nans0.end()) {
                nans0.erase(i);
            } else {
                nans0.emplace((t + n - 1) % n);
            }
            if (auto i = ans0.find((t + 1) % n);i != ans0.end()) {
                ans1.emplace(*i);
                ans0.erase(i);
            } else if (i = ans1.find((t + 1) % n);i != ans1.end()) {
                ans0.emplace(*i);
                ans1.erase(i);
            } else if (i = nans0.find((t + 1) % n);i != nans0.end()) {
                nans0.erase(i);
            } else {
                nans0.emplace((t + 1) % n);
            }
        }
    }
    n = (int) ans_v.size();
    cout << n << endl;
    rep(i, 0, n) {
        cout << ans_v[i] + 1 << " \n"[i == n - 1];
    }
}

int main() {
    IOS
    int t;
    cin >> t;
    while (t--)solve();
}