#include <bits/stdc++.h>   using namespace std;   string s;   int a[10005], f[10005][4], q[28000], h2[10005], h3[10005], n;   int main() {     ios::sync_with_stdio(0);     cin >> s;     n = s.size();     for (int i = 1; i <= n; i++) a[i] = s[i - 1] -  a  + 1;     for (int i = 6; i <= n; i++)       h2[i] = a[i] * 900 + a[i + 1] * 30, h3[i] = h2[i] + a[i + 2];     if (n < 7) {       printf( 0 n );       return 0;     }     f[n + 1][2] = f[n + 1][3] = 1, f[n - 1][2] = 1;     q[h2[n - 1]] = 1;     for (int i = n - 2; i > 5; i--) {       if (f[i + 2][3] || (f[i + 2][2] && h2[i] != h2[i + 2]))         f[i][2] = 1, q[h2[i]] = 1;       if (f[i + 3][2] || (f[i + 3][3] && h3[i] != h3[i + 3]))         f[i][3] = 1, q[h3[i]] = 1;     }     int ans = 0;     for (int i = 1; i <= 27500; i++) ans += q[i];     printf( %d n , ans);     for (int i = 1; i <= 27500; i++) {       if (!q[i]) continue;       if (i % 30)         printf( %c%c%c n , (i / 900) + 96, ((i % 900) / 30) + 96, (i % 30) + 96);       else         printf( %c%c n , (i / 900) + 96, ((i % 900) / 30) + 96);     }     return 0;   }   