[백준 1764번 / C++ / Silver IV] 듣보잡

#include <iostream>
#include <string>	
#include <algorithm>
#include <vector>
using namespace std; 
int main() {
	int a, b; 
	cin >> a >> b;
	int cnt = 0;
	int i, j, k; 
	vector<string>A;
	vector<string>B;
	for (i = 0; i < a; i++) {
		string s; 
		cin >> s;
		A.push_back(s);
	}
	sort(A.begin(), A.end());
	for (i = 0; i < b; i++) {
		string s; 
		cin >> s;
		
		if (binary_search(A.begin(), A.end(), s)) {
			B.push_back(s);
			cnt++;
		}
	}
	sort(B.begin(), B.end());
	cout << cnt << endl;
	for (string s : B)
		cout << s << endl;
}