#pragma GCC optimize("O3, unroll-loops, Ofast")
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
#define tiii tuple<char,char,cg>
int mod = 998244353; 
vector<vector<vector<int32_t>>> cnt(8, vector<vector<int32_t>>(7, vector<int32_t>(7)));
vector<char> cur;
int res = 0;
set<pii> edges;
void gen(int n){
    if(n == 0){ 
        for(int l = 3; l <= 10; l++){
            int cp = 1;
            for(auto e : edges){
                cp *= cnt[l-3][cur[e.first]][cur[e.second]];
                cp %= mod;
                if(cp == 0) break;
            }
        
            res += cp;
            res %= mod;
        }
        return;
    }
    for(int i = 0; i < 7; i++){
        cur.push_back(i);
        gen(n-1);
        cur.pop_back();
    }   
}
int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    // vector<tiii> arr(n);
    set<string> occ;
    for(int i = 0; i < n; i++){
        string s;
        cin >> s;
        string r = s;
        reverse(r.begin(),r.end());
        // arr[i] = {s.size(), s[0]-'a', s.back()-'a'};
        if(occ.count(r)   || occ.count(s)) continue; 
        char ind1 = s[0]-'a';
        char ind2 = s.back()-'a';
        cnt[s.size()-3][ind1][ind2]++;
    
        if(r != s){
            cnt[r.size()-3][r[0]-'a'][r.back()-'a']++;
        }
    }
    auto start = clock();
    for(char v = 0; v < 4; v++){
        auto ins = [&](char a, char b){
            if(a > b) swap(a,b);
            edges.insert({a,b});
        };
        ins(v, (v+1)%4);
        ins(v, (v+3)%4);
        ins(v, v+4);
        ins(4+v, 4+((v+1)%4));
        ins(4+v, 4+((v+3)%4));
    }
    
    gen(8);
    
     
    cout << res << endl; 
}
Compilation message (stderr)
cubeword.cpp:1:47: warning: bad option '-f unroll-loops' to pragma 'optimize' [-Wpragmas]
    1 | #pragma GCC optimize("O3, unroll-loops, Ofast")
      |                                               ^
cubeword.cpp:1:47: warning: bad option '-f Ofast' to pragma 'optimize' [-Wpragmas]
cubeword.cpp:15:15: warning: bad option '-f unroll-loops' to attribute 'optimize' [-Wattributes]
   15 | void gen(int n){
      |               ^
cubeword.cpp:15:15: warning: bad option '-f Ofast' to attribute 'optimize' [-Wattributes]
cubeword.cpp:37:14: warning: bad option '-f unroll-loops' to attribute 'optimize' [-Wattributes]
   37 | int32_t main(){
      |              ^
cubeword.cpp:37:14: warning: bad option '-f Ofast' to attribute 'optimize' [-Wattributes]
cubeword.cpp: In function 'int32_t main()':
cubeword.cpp:67:38: warning: bad option '-f unroll-loops' to attribute 'optimize' [-Wattributes]
   67 |         auto ins = [&](char a, char b){
      |                                      ^
cubeword.cpp:67:38: warning: bad option '-f Ofast' to attribute 'optimize' [-Wattributes]| # | Verdict | Execution time | Memory | Grader output | 
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