// 基本テンプレート #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; #define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++) #define repq(i,a,n) for(int (i)=(a); (i)<=(n); (i)++) #define repr(i,a,n) for(int (i)=(a); (i)>=(n); (i)--) #define int long long int template void chmax(T &a, T b) {a = max(a, b);} template void chmin(T &a, T b) {a = min(a, b);} template void chadd(T &a, T b) {a = a + b;} typedef pair pii; typedef long long ll; int dx[] = {0, 0, 1, -1}; int dy[] = {1, -1, 0, 0}; constexpr ll INF = 1001001001001001LL; constexpr ll MOD = 1000000007LL; int diff[25][25]; int dp[1 << 20], enumerate[1 << 20], rec[25]; int N; vector vs; signed main() { cin >> N; rep(i,0,N) { string s; cin >> s; vs.push_back(s); } rep(i,0,N) rep(j,i+1,N) { int idx = 0, ans = -1; while(idx < vs[i].length() && idx < vs[j].length()) { if(vs[i][idx] != vs[j][idx]) { ans = idx; break; } else idx++; } if(ans < 0) ans = min(vs[i].length(), vs[j].length()); diff[i][j] = diff[j][i] = ans + 1; } /* rep(i,0,N) { rep(j,0,N) printf("%lld ", diff[i][j]); cout << endl; } */ enumerate[(1 << N) - 1] = 1; repr(bit,(1<> i & 1) { int ma = 1; rep(j,0,N) if(bit >> j & 1) chmax(ma, diff[i][j]); int nbit = bit ^ (1 << i); (enumerate[nbit] += enumerate[bit]) %= MOD; (dp[nbit] += (dp[bit] + enumerate[bit] * ma) % MOD) %= MOD; } } // rep(i,0,1<