输入样例：

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

输出样例：

3
150702193604190912

solution

#include<iostream>
#include<string>
#include<map>
using namespace std;
int main(){
	int n, m, ans = 0;
	string s, old1 = "null", old2 = "null";
	map<string, int> mp;//mp[s]==1则身份证为s的来宾是校友
	cin >> n;
	for(int i = 0; i < n; i++){
		cin >> s;
		mp[s] = 1;
	}
	cin >> m;
	for(int i = 0; i < m; i++){
		cin >> s;
		if(old1.size() < 10 || old1.substr(6, 8) > s.substr(6, 8)) old1 = s;//年龄大==>出生年月小
		if(mp[s]){
			ans++;
			if(old2.size() < 10 || old2.substr(6, 8) > s.substr(6, 8)) old2 = s;
		}
	}
	if(ans == 0) cout << ans << endl << old1;//没有校友来，则输出最年长的来宾
	else cout << ans << endl << old2;//有校友来，则输出最年长的校友
	return 0;
}