Problem: You are standing in front of the room with great treasures. The only thing stopping you is the door with a push-button combination lock. This lock has d buttons with digits from 0 to d - 1. Whenever you press a button, it stays pushed down. You can not pop back up just one button, but there is a "RESET" button — pressing it pops up all other buttons. Initially, no buttons are pushed down.

The door instantly opens when some specific set of digits is pushed down. Sadly, you don't know the password for it. Having read the documentation for this specific lock, you found out that there are n possible passwords for this particular lock. 

Find the shortest sequence of button presses, such that all possible passwords appear at least once during its execution. Any shortest correct sequence of button presses will be accepted.

Input

The first line contains two integers d and n (1 ≤ d ≤ 10; 1 ≤ n ≤ 2^d - 1). Next n lines describe possible passwords. Each line contains a string s_i of d zeros and ones: for all j from 1 to d the j-th character is 1 iff the button with the digit j - 1 must be pushed down.

All strings s_i are different, and each string contains at least one 1.

Output

On the first line, print the number k — the minimum number of button presses. On the second line, print k tokens, describing the sequence. Whenever you press a button with a digit, print that digit. Whenever you press "RESET", print "R".

Examples

Input


2 2
10
11


Output


2
0 1 


Input


3 4
001
111
101
011


Output


6
2 0 R 1 2 0 

Note

In the second example, the sequence 1 2 R 2 0 1 is also possible.

Solution (in CPP):

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

using ll = long long;
using ld = long double;
const ld eps = 1e-8;
// for matching the kactl notes
#define sz(x) ((int)x.size())
#define rep(i,a,b) for (int i = (int)(a); i < (int)(b); ++i) 
#define all(a) (a).begin(), (a).end()
// #define constexpr(...) (__VA_ARGS__)  
// DEBUGING TEMPLETE ////////////////////////////////////////////////////////////////////////{{{
#define db(val) "["#val" = "<<(val)<<"] "
#define CONCAT_(x, y) x##y
#define CONCAT(x, y) CONCAT_(x, y)
#ifdef LOCAL_DEBUG   
#   define clog cerr << flush << string(__db_level * 2, ' ')
#   define DB() debug_block CONCAT(dbbl, __LINE__)
    int __db_level = 0;
    struct debug_block {
        debug_block() { clog << "{" << endl; ++__db_level; }
        ~debug_block() { --__db_level; clog << "}" << endl; }
    };
#else
#   define clog if (0) cerr
#   define DB(...)
#endif

template<class U, class V> ostream& operator<<(ostream& out, const pair<U, V>& p) {
    return out << "(" << p.first << ", " << p.second << ")";
}

template<size_t i, class T> ostream& print_tuple_utils(ostream& out, const T& tup) {
    if constexpr(i == tuple_size<T>::value) return out << ")"; 
    else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); 
}

template<class ...U> ostream& operator<<(ostream& out, const tuple<U...>& tup) {
    return print_tuple_utils<0, tuple<U...>>(out, tup);
}

template<class Con, class = decltype(begin(declval<Con>()))>
typename enable_if<!is_same<Con, string>::value, ostream&>::type
operator<<(ostream& out, const Con& container) { 
    out << "{";
    for (auto it = container.begin(); it != container.end(); ++it)
        out << (it == container.begin() ? "" : ", ") << *it;
    return out << "}";
}
// ACTUAL SOLUTION START HERE ////////////////////////////////////////////////////////////////}}}

using vi = vector<int>;
const int inf = INT_MAX / 100;
const int magic_small_prio_lim = 15;  // not magic tho, because the max path is only like 10 or 11 (d or d + 1)

template<class T>
struct SmallPrioQueue {
    vector<vector<T>> qu;
    int ptr;
    SmallPrioQueue(int lim): qu(lim), ptr(0) {}
    SmallPrioQueue(): SmallPrioQueue(magic_small_prio_lim) {}
    void push(int cost, const T& val) {
        ptr= min(ptr, cost);
        qu[cost].push_back(val);
    }
    int inc() {
        while (ptr < sz(qu) and qu[ptr].empty()) ++ptr;
        if (ptr == sz(qu)) return -1;
        return ptr;
    }
    pair<int, T> pop() {
        if (inc() == -1) return {-1, T()};
        auto ans = qu[ptr].back();
        qu[ptr].pop_back();
        return {ptr, ans};
    }
};

struct MCMF {
    int n;
    vector<vi> cap, flow, cost;
    vector<vi> gr;
    MCMF(int n_)
    : n(n_), cap(n, vi(n)), flow(cap), cost(cap), gr(n) { }
    
    void add_edge(int u, int v, int ecap, int ecost) {
        clog << "add edge" << db(u) << db(v) << db(ecap) << db(ecost) << endl;
        gr[u].push_back(v);
        gr[v].push_back(u);
        cap[u][v] = ecap;
        cost[u][v] = ecost;
        cost[v][u] = -ecost;
    }
        
    vector<int> par;
    vector<int> dist;
    vector<bool> vis;
    bool path(int s, int t) {
        DB(); clog << "path" << endl;
        par.assign(n, -1);
        dist.assign(n, inf);
        vis.assign(n, false);
        par[s] = s;
        dist[s] = 0;
        SmallPrioQueue<int> prio;
        prio.push(0, s);
        while (prio.inc() != -1) {
            auto [d, u] = prio.pop();
            if (dist[u] < d) continue;
            clog << db(u) << db(d) << db(par[u]) << endl;
            vis[u] = true;
            if (u == t) break;
            for (auto v: gr[u]) {
                if (vis[v]) continue;
                if (cap[u][v] == flow[u][v]) continue;
                int nd = dist[u] + cost[u][v];
                if (nd >= dist[v]) continue;
                clog << "add " << db(v) << db(nd) << endl;
                par[v] = u;
                dist[v] = nd;
                prio.push(nd, v);
            }
        }
        return par[t] != -1;
    }
    
    int inc_flow(int s, int t, int lim = inf) {
        DB(); clog << "inc flow" << endl;
        clog << db(s) << db(t) << db(lim) << endl;
        int flow_inc = 0;
        while (lim and path(s, t)) {
            DB(); clog << "flow " << endl;
            int cur_flow = lim;
            for (int u = t; u != s; u = par[u])
                cur_flow = min(cur_flow, cap[par[u]][u] - flow[par[u]][u]);
            clog << db(cur_flow) << endl;
            for (int u = t; u != s; u = par[u]) {
                clog << db(u) << db(par[u]) << db(cap[par[u]][u]) << db(flow[par[u]][u])<< endl;
                flow[par[u]][u] += cur_flow;
                flow[u][par[u]] -= cur_flow;
            }
            lim -= cur_flow;
            flow_inc += cur_flow;
        }
        return flow_inc;
    }
    
    int get_cost() { 
        int ans = 0;
        rep(i, 0, n) rep(f, 0, n) {
            if (cost[i][f] > 0) {
                ans += flow[i][f] * cost[i][f];
                if (flow[i][f]) clog << db(i) << db(f) << db(flow[i][f]) <<endl;
            }
        }
        return ans;
    } 
};

int d, n;
vector<int> term;
int main() {
#ifdef LOCAL
    freopen("main.inp", "r", stdin); 
    freopen("main.out", "w", stdout);  
    freopen(".log", "w", stderr);
#endif
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    cin >> d >> n;
    term.resize(n);
    for(auto& i: term) {
        string s; cin >> s;
        i = 0;
        rep(bit, 0, d) i |= (s[bit] == '1') << bit;
    }
    term.push_back(0);
    sort(all(term), [&](int u, int v) { return __builtin_popcount(u) < __builtin_popcount(v); });
    
    ++n;
    MCMF mcmf(2 * n + 1);
    int sink = 2 * n;
    
    rep(i, 0, n) rep(f, 0, i) {
        if ((term[i] & term[f]) == term[f]) {
            mcmf.add_edge(2 * i, 2 * f + 1, 1, __builtin_popcount(term[i] ^ term[f]));
        }
    }
    
    mcmf.add_edge(1, sink, n, 1);  // cost == 1 for reset
    rep(i, 1, n) mcmf.add_edge(2 * i + 1, sink, 1, 0);
    
    rep(i, 1, n) {
        int inced = mcmf.inc_flow(2 * i, sink, 1);
        clog << db(i) << db(inced) << db(mcmf.get_cost()) << endl;
    }
    
    vector<int> path;
    function<bool(int)> dfs = [&](int u) {
        if (u == 0) {
            path.push_back(0);
            return true;
        }
        for (auto virtual_v: mcmf.gr[2 * u]) {
            int v = virtual_v / 2;
            if (v == n or mcmf.flow[2 * u][virtual_v] == 0) continue;
            if (dfs(v)) {
                path.push_back(u);
                mcmf.flow[2 * u][virtual_v] --;
                return true;
            }
        }
        return false;
    };
    
    vector<int> ans;
    for (int i = n; i-- > 1; ) {
        path.clear();
        if (!dfs(i)) continue;
        if (sz(ans)) ans.push_back(-1);
        int prev = 0;
        for (auto f: path) {
            int u = term[f];
            int diff = prev ^ u;
            prev ^= diff;
            rep(bit, 0, d)
                if ((diff >> bit) & 1) ans.push_back(bit);
        }
    }
    cout << sz(ans) << '\n';
    for (auto i: ans) {
        if (i == -1) cout << "R ";
        else cout << i << ' ';
    }
    
    return 0;
}

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