1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 typedef struct Node {
 5     Node* fail;
 6     Node* next[26];
 7     bool sign;
 8     Node() { fail = NULL; for(int i = 0; i < 26; i++) next[i] = NULL; }
 9 }Node;
10 
11 const int maxn = 1000100;
12 Node* rt;
13 int n;
14 char tmp[maxn];
15 
16 void insert(Node* rt, char* str) {
17     Node* tmp = rt;
18     for(int i = 0; str[i]; i++) {
19         int idx = str[i] - ‘a‘;
20         if(tmp->next[idx] == NULL) tmp->next[idx] = new Node();
21         tmp = tmp->next[idx];
22     }
23     tmp->sign = 1;
24 }
25 
26 void build(Node* rt) {
27     Node* cur;
28     Node* tmp;
29     queue<Node*> q;
30     q.push(rt);
31     while(!q.empty()) {
32         cur = q.front(); q.pop();
33         for(int i = 0; i < 26; i++) {
34             if(!cur->next[i]) continue;
35             if(cur == rt) cur->next[i]->fail = rt;
36             else {
37                 tmp = cur->fail;
38                 do {
39                     if(tmp->next[i]) {
40                         cur->next[i]->fail = tmp->next[i];
41                         break;
42                     }
43                 } while(tmp = tmp->fail);
44                 if(tmp == NULL) cur->next[i]->fail = rt;
45             }
46             q.push(cur->next[i]);
47         }
48     }
49 }
50 
51 bool query(Node* rt, char* str) {
52     Node* cur = rt;
53     for(int i = 0; str[i]; i++) {
54         int idx = str[i] - ‘a‘;
55         while(cur->next[idx] == NULL && cur != rt) cur = cur->fail;
56         cur = cur->next[idx];
57         if(cur == NULL) {
58             cur = rt;
59             continue;
60         }
61         if(cur->sign) return 1;
62     }
63     return 0;
64 }
65 
66 int main() {
67     // freopen("in", "r", stdin);
68     while(~scanf("%d", &n)) {
69         rt = new Node();
70         for(int i = 0; i < n; i++) {
71             scanf("%s", tmp);
72             insert(rt, tmp);
73         }
74         build(rt);
75         scanf("%s", tmp);
76         if(query(rt, tmp)) puts("YES");
77         else puts("NO");
78     }
79     return 0;
80 }