🐣 문제

링크 : https://www.acmicpc.net/problem/1764

🐥 코드

/*
문제 : 듣보잡
링크 : https://www.acmicpc.net/problem/1764
*/

#include <iostream>
#include <map>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    int N, M;
    cin >> N >> M;
    
    map<string, int> m;
    vector<string> v;
    for(int i = 0; i < N+M; i++){
        string s;
        cin >> s;
        m[s]++;
        if(m[s] > 1) v.push_back(s);
    }

    sort(v.begin(), v.end());

    cout << v.size() << '\n';
    for(auto i : v) cout << i << '\n';

    return 0;
}