#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <queue>
#include <map>
using namespace std;

struct pawn {
    string S;
    int distance;
    vector<int> v;
};
bool check_if_pawns_are_ok(string &s) {
    if(s[0] == '1') {
        int idx = -1;
        for(int i = 0; i < (int) s.size(); i++) {
            if(s[i] != '1') {
                idx = i;
                break;
            }
        }
        if(idx != -1) {
            while(s[idx] == '0' and idx < (int) s.size()) {
                idx++;
            }
            for(int i = idx; i < (int) s.size(); i++) {
                if(s[i] != '2') {
                    return false;
                }
            }
         
        }
        return true;
    }
    return false;
}
map<string, bool> visited;
map<int, pair<string, int> > mapa;
int main()
{
    ios_base::sync_with_stdio(false);
    int n;
    cin >> n;
    vector<int> v(n);
    string s = "";
    for(int i = 0; i < n; i++) {
        cin >> v[i];
        s += (v[i] + '0');
    }
    queue<pawn> Q;
    vector<int> emp;
    visited[s] = true;
    pawn tmp;
    tmp.S = s;
    tmp.distance = 0;
    tmp.v = emp;
    Q.push(tmp);
    
    while(!Q.empty()) {
        tmp = Q.front();
        Q.pop();
        if(check_if_pawns_are_ok(tmp.S)) {
            cout << tmp.distance << endl;
            // print the steps
            for(int i = 0; i < tmp.v.size(); i++) {
                cout << tmp.v[i] << " ";
            }
            return 0;
        }
        for(int i = 0; i < (int) tmp.S.size(); i++) {
            if(tmp.S[i] == '1') {
                if(i - 1 >= 0 and tmp.S[i - 1] == '0') {
                    string ps = tmp.S;
                    ps[i] = '0';
                    ps[i - 1] = '1';
                    if(!visited[ps]) {
                        visited[ps] = true;
                        pawn new_pawn;
                        new_pawn.S = ps;
                        new_pawn.distance = tmp.distance + 1;
                        vector<int> steps = tmp.v;
                        steps.push_back(i + 1);
                        new_pawn.v = steps;
                        Q.push(new_pawn);
                    }
                }
                if(i - 2 >= 0 and tmp.S[i - 1] != '0' and tmp.S[i - 2] == '0') {
                    string ps = tmp.S;
                    ps[i] = '0';
                    ps[i - 2] = '1';
                    if(!visited[ps]) {
                        visited[ps] = true;
                        pawn new_pawn;
                        new_pawn.S = ps;
                        new_pawn.distance = tmp.distance + 1;
                        vector<int> steps = tmp.v;
                        steps.push_back(i + 1);
                        new_pawn.v = steps;
                        Q.push(new_pawn);
                    }
                }
                
            }
            else if(tmp.S[i] == '2') {
                if(i + 1 < (int) tmp.S.size() and tmp.S[i + 1] == '0') {
                    string ps = tmp.S;
                    ps[i] = '0';
                    ps[i + 1] = '2';
                    if(!visited[ps]) {
                        visited[ps] = true;
                        pawn new_pawn;
                        new_pawn.S = ps;
                        new_pawn.distance = tmp.distance + 1;
                        vector<int> steps = tmp.v;
                        steps.push_back(i + 1);
                        new_pawn.v = steps;
                        Q.push(new_pawn);
                    }
                }
                if(i + 2 < (int) tmp.S.size() and tmp.S[i + 1] != '0' and tmp.S[i + 2] == '0') {
                    string ps = tmp.S;
                    ps[i] = '0';
                    ps[i + 2] = '2';
                    if(!visited[ps]) {
                        visited[ps] = true;
                        pawn new_pawn;
                        new_pawn.S = ps;
                        new_pawn.distance = tmp.distance + 1;
                        vector<int> steps = tmp.v;
                        steps.push_back(i + 1);
                        new_pawn.v = steps;
                        Q.push(new_pawn);
                    }
                }
            }
        }
    }
    
    
    return 0;
}