#include <bits/stdc++.h>
using namespace std;

int main() {
    int n, m;
    cin >> n;
    set<string> store1;
    set<string> store2;
    set<string> out;
    for (int i = 0; i < n; i++) {
        string temp;
        cin >> temp;
        store1.insert(temp);
    }
    cin >> m; 
    for (int i = 0; i < m; i++) {
        string temp;
        cin >> temp;
        store2.insert(temp);
    }

    for (string x : store1) {
        if (!store2.count(x)) {
            out.insert(x);
        }
    }
    for (string x : store2) {
        if (!store1.count(x)) {
            out.insert(x);
        }
    }

    cout<<out.size()<<endl;
    for (string x : out) {
        cout<<x<<endl;
    }
}