1121. Damn Single (25)

//
// Created by aleafall on 16-12-10.
//

#include <bits/stdc++.h>

using namespace std;

const int maxn = 100005;
bool vis[maxn] = {0};

int main() {
int n, x1, x2, m;
int a[maxn];
map<int, int> mp;
vector<int> ans;
cin >> n;
for (int i = 0; i < n; ++i) {
scanf("%d %d", &x1, &x2);
mp[x1] = x2;
mp[x2] = x1;
}
cin >> m;
for (int i = 0; i < m; ++i) {
scanf("%d", &a[i]);
vis[a[i]] = 1;
}
for (int i = 0; i < m; ++i) {
if (!(vis[a[i]] && vis[mp[a[i]]])) {
ans.push_back(a[i]);
}
}
cout << ans.size() << endl;
sort(ans.begin(), ans.end());
for (int i = 0; i < ans.size(); ++i) {
if (i < ans.size() - 1) {
printf("%05d ", ans[i]);
} else {
printf("%05d\n", ans[i]);
}
}
return 0;
}