#include <bits/stdc++.h>   using namespace std;   struct edge {     int v, nxt, c;   } e[1505 * 1505 * 2];   int p[1505], eid;   void init() {     memset(p, -1, sizeof p);     eid = 0;   }   void insert(int u, int v, int c) {     e[eid].v = v;     e[eid].c = c;     e[eid].nxt = p[u];     p[u] = eid++;   }   void add(int u, int v, int c) {     insert(u, v, c);     insert(v, u, 0);   }   int ch[10000005][2], cnt[10000005], tot, ys[1505], nxt[10000005], g[755][755],       L[1505], R[1505], ha[10000005];   string st;   queue<int> q;   void insert(int id) {     int p = 0, len = st.length();     L[id] = ha[0] + 1;     for (int i = 0; i < len; i++) {       ha[++ha[0]] = st[i] -  a ;       if (!ch[p][st[i] -  a ]) ch[p][st[i] -  a ] = ++tot;       p = ch[p][st[i] -  a ];     }     cnt[p] = id;     R[id] = ha[0];   }   void build() {     for (int i = 0; i < 2; i++)       if (ch[0][i]) q.push(ch[0][i]);     while (q.size()) {       int u = q.front();       q.pop();       for (int i = 0; i < 2; i++) {         if (!ch[u][i])           ch[u][i] = ch[nxt[u]][i];         else           nxt[ch[u][i]] = ch[nxt[u]][i], q.push(ch[u][i]);       }     }   }   int vis[10000005];   void run(int id) {     int p = 0;     vis[0] = 1;     for (int i = L[id]; i <= R[id]; i++) {       p = ch[p][ha[i]];       int pp = p, tt;       while (pp) {         if (cnt[pp] && cnt[pp] != id) {           g[id][cnt[pp]] = 1;           break;         }         pp = nxt[pp];       }       int haha = pp;       pp = p;       while (pp) {         if (cnt[pp] && cnt[pp] != id) {           break;         }         tt = pp;         pp = nxt[pp];         nxt[tt] = haha;       }     }   }   int dis[1505], S, T, n;   int bfs() {     memset(dis, -1, sizeof dis);     dis[S] = 1;     q.push(S);     while (q.size()) {       int u = q.front();       q.pop();       for (int i = p[u]; i + 1; i = e[i].nxt) {         int v = e[i].v;         if (dis[v] == -1 && e[i].c) {           dis[v] = dis[u] + 1;           q.push(v);         }       }     }     return dis[T] != -1;   }   int dfs(int u, int flow) {     if (u == T) return flow;     int ret = 0;     for (int i = p[u]; i + 1; i = e[i].nxt) {       int c = e[i].c, v = e[i].v;       if (c && dis[v] == dis[u] + 1) {         int tmp = dfs(v, min(flow, c));         ret += tmp, flow -= tmp;         e[i].c -= tmp, e[i ^ 1].c += tmp;         if (!flow) break;       }     }     if (!ret) dis[u] = -1;     return ret;   }   int Dinic() {     int ret = 0;     for (; bfs();) ret += dfs(S, 2147483646 / 2);     return ret;   }   int main() {     ios::sync_with_stdio(false);     init();     cin >> n;     T = 2 * n + 1;     for (int i = 1; i <= n; i++) cin >> st, insert(i);     build();     for (int i = 1; i <= n; i++) run(i);     for (int k = 1; k <= n; k++)       for (int i = 1; i <= n; i++)         for (int j = 1; j <= n; j++) g[i][j] |= (g[i][k] & g[k][j]);     for (int i = 1; i <= n; i++)       for (int j = 1; j <= n; j++)         if (g[i][j] && i != j) add(i, j + n, 1);     for (int i = 1; i <= n; i++) add(S, i, 1), add(i + n, T, 1), vis[i + n] = 0;     cout << n - Dinic() << endl;     for (int i = 1; i <= n; i++)       if (dis[i] != -1 && dis[i + n] == -1) cout << i <<    ;     return 0;   }