School day (summer vacation daily question 2)

2019 Zhejiang University will celebrate its establishment in 122 Anniversary of the .

In preparation for the school day , Alumni Association collects all alumni ID number. .

Now I need you to write a program , The ID number of all the people who attend the celebration. , Count how many alumni have come .

Input format
The input gives a positive integer on the first line $N$.

And then $N$ That's ok , Each row gives an alumni ID number. （$18$ Bits consist of numbers and uppercase letters X Composed string ）. The title ensures that the ID number is not duplicated. .

Then give the information of all the people who came to attend the school celebration ：

First is a positive integer $M$.

And then $M$ That's ok , Each row gives the ID number of a person. . The title ensures that the ID number is not duplicated. .

Output format
First, output the number of alumni participating in the celebration in the first line .

Then output the oldest alumni ID number in the second row. —— Pay attention to ID No $7-14$ Bit gives yyyymmdd Birthday in format .

If no alumni come , Then output the ID number of the oldest guests in the second row. . The title guarantees that such alumni or guests must be the only one .

Data range
$1\le N,M\le 10^5$

sample input ：

5
372928196906118710
610481197806202213
440684198612150417
13072819571002001X
150702193604190912
6
530125197901260019
150702193604190912
220221196701020034
610481197806202213
440684198612150417
370205198709275042

sample output ：

3
150702193604190912

---

#include<iostream>
#include<unordered_set>

using namespace std;

const int N = 100010;

int n, m;
unordered_set<string> S;

int main(){
    
    
    
    scanf("%d", &n);
    char in_str[20];
    for(int i = 0; i < n; i++)
        scanf("%s", in_str), S.insert(in_str);
       
    scanf("%d", &m);
    int cnt = 0, last = 0;
    string res = "", s;
    for(int i = 0; i < m; i++){
    
        
        scanf("%s", in_str);
        s = in_str;
        int flag = S.count(s);
        if(flag) cnt++;
        if(res.empty() || flag > last || 
        (flag == last && s.substr(6, 8) < res.substr(6, 8))){
    
            
            res = s;
            last = flag;
        }
    }
    
    printf("%d\n%s", cnt, res.c_str());
    
    return 0;
}