func_code_string: #include <bits/stdc++.h>       using namespace std;       #define SPEED ios::sync_with_stdio(false); cin.tie(0); cout.tie(0)   #define fileio freopen( in.in ,  r , stdin),freopen( out.out ,  w , stdout);   #define ll long long   #define int long long   #define FF first   #define SS second   #define mp make_pair   #define pb push_back   #define pii pair<ll,ll>   #define pll pair<long long,long long>   #define sd(x) scanf( %d ,&x)   #define slld(x) scanf( %lld ,&x)   #define pd(x) prllf( %d n ,x)   #define plld(x) prllf( %lld n ,x)   #define pss prllf   #define MOD 1000000007   #define eps 0.00001   #define endl   n    #define debug(n1) cout<<n1<<endl   ll n,k,s[1005],e[1005],c[1005];   bool y[1005];   const ll INF = 1e17+5;   int mm[100005];   vector<int>temp[100005];      struct MinimumCostMaximumFlow {     typedef ll Index; typedef ll Flow; typedef ll Cost;     static const Flow InfCapacity = INF;     struct Edge {       Index to; Index rev;       Flow capacity; Cost cost;     };     vector<vector<Edge> > g;     void init(Index n) { g.assign(n, vector<Edge>()); }     void addEdge(bool inv,Index i, Index j, Flow capacity = InfCapacity, Cost cost = Cost() ) {       Edge e, f; e.to = j, f.to = i; e.capacity = capacity, f.capacity = 0; e.cost = cost, f.cost = -cost;       if(inv)       {           temp[i].push_back(mm[i]);       }       mm[i]++;       mm[j]++;          g[i].push_back(e); g[j].push_back(f);       g[i].back().rev = (Index)g[j].size() - 1; g[j].back().rev = (Index)g[i].size() - 1;     }     void addB(Index i, Index j, Flow capacity = InfCapacity, Cost cost = Cost()) {       addEdge(0,i, j, capacity, cost);       addEdge(0,j, i, capacity, cost);     }        pair<Cost, Flow> minimumCostMaximumFlow(Index s, Index t, Flow f = InfCapacity, bool useSPFA = false) {       ll n = g.size();       vector<Cost> dist(n); vector<Index> prev(n); vector<Index> prevEdge(n);       pair<Cost, Flow> total = make_pair(0, 0);       vector<Cost> potential(n);       while(f > 0) {         fill(dist.begin(), dist.end(), INF);         if(useSPFA || total.second == 0) {           deque<Index> q;           q.push_back(s); dist[s] = 0; vector<bool> inqueue(n);           while(!q.empty()) {             Index i = q.front(); q.pop_front(); inqueue[i] = false;             for(Index ei = 0; ei < (Index)g[i].size(); ei ++) {               const Edge &e = g[i][ei]; Index j = e.to; Cost d = dist[i] + e.cost;               if(e.capacity > 0 && d < dist[j]) {                 if(!inqueue[j]) {                   inqueue[j] = true;                   q.push_back(j);                 }                 dist[j] = d; prev[j] = i; prevEdge[j] = ei;               }             }           }         } else {           vector<bool> vis(n);           priority_queue<pair<Cost, Index> > q;           q.push(make_pair(-0, s)); dist[s] = 0;           while(!q.empty()) {             Index i = q.top().second; q.pop();             if(vis[i]) continue;             vis[i] = true;             for(Index ei = 0; ei < (Index)g[i].size(); ei ++) {               const Edge &e = g[i][ei];               if(e.capacity <= 0) continue;               Index j = e.to; Cost d = dist[i] + e.cost + potential[i] - potential[j];               if(dist[j] > d) {                 dist[j] = d; prev[j] = i; prevEdge[j] = ei;                 q.push(make_pair(-d, j));               }             }           }         }         if(dist[t] == INF) break;         if(!useSPFA) for(Index i = 0; i < n; i ++) potential[i] += dist[i];             Flow d = f; Cost distt = 0;         for(Index v = t; v != s; ) {           Index u = prev[v]; const Edge &e = g[u][prevEdge[v]];           d = min(d, e.capacity); distt += e.cost; v = u;         }         f -= d; total.first += d * distt; total.second += d;         for(Index v = t; v != s; v = prev[v]) {           Edge &e = g[prev[v]][prevEdge[v]];           e.capacity -= d; g[e.to][e.rev].capacity += d;         }       }       return total;     }   };          int find_num(string ss)   {       int ans=0;       int tt=1;       reverse(ss.begin(),ss.end());          for(auto i:ss)       {           ans+=(i- 0 )*tt;           tt*=2;       }       return ans;   }            vector<vector<int> >adj;   int sz[1000005];   int vis[1000005];   int a[100005];   vector<string>fi;   int d;      void print(int yy)   {       for(int i=0;i<10;i++)       {           if(((1<<i)&yy))           {               fi.push_back(to_string(d-i-1));           }       }   }      void dfs(int ver,int x)   {       vis[ver]=1;       print(a[ver]^x);       int cnt=0;             for(auto i:adj[ver])       {           if(vis[i]==0)           {               if(cnt)               {                   fi.push_back( R );                   print(a[ver]);                   dfs(i,a[ver]);               }               else               {                   dfs(i,a[ver]);               }               cnt++;           }       }   }      signed main()   {       ios_base::sync_with_stdio(false);    cin.tie(NULL);     cout.tie(0);          #ifndef ONLINE_JUDGE       if(fopen( INPUT.txt , r ))       {           freopen( INPUT.txt , r ,stdin);           freopen( OUTPUT.txt , w ,stdout);       }      #endif                    int n;       cin>>d>>n;       string se[n];       for(int i=0;i<n;i++)       {           cin>>se[i];           a[i+1]=find_num(se[i]);       }          adj.resize(n+1);          MinimumCostMaximumFlow kad;       int source=0;       int sink=2*n+5;          kad.init(2*n+10);          for(int i=1;i<=n;i++)       {           for(int j=1;j<=n;j++)           {               if(i!=j)               {                   if((a[i]&a[j])==a[j])                   {                       kad.addEdge(1,n+j,i,1,-(__builtin_popcount(a[j])+1));                   }               }           }              kad.addEdge(0,i,n+i,1,0);           kad.addEdge(0,source,i,1,0);           kad.addEdge(0,n+i,sink,1,-(__builtin_popcount(a[i])+1));       }          kad.addEdge(0,source,sink,n,0);          pair<int,int> ans=kad.minimumCostMaximumFlow(source,sink,n,0);          for(int i=n+1;i<=2*n;i++)       {           for(auto j:temp[i])           {               if(kad.g[i][j].capacity==0)               {                   adj[i-n].push_back(kad.g[i][j].to);               }           }       }          set<pair<int,int> >ss;       int cc=0;       for(int i=1;i<=n;i++)       {           ss.insert({a[i],i});       }          while(!ss.empty())       {           auto j=ss.begin();           if(vis[j->second])           {               ss.erase(j);               continue;           }           if(cc)               fi.push_back( R );           cc++;           dfs(j->second,0);       }          cout<<fi.size()<<  n ;       for(auto i:fi)           cout<<i<<   ;            }