Shared code

#include <bits/stdc++.h>
 
using namespace std;
 
void solve() {
    int n, m;
    cin >> n >> m;
    // 將 vector 換成 multiset，因為 multiset 插入、搜尋、刪除都是 O(log n)
    multiset<int> st;
    for (int i = 0; i < n; ++i) {
        int h;
        cin >> h;
        st.insert(h);
    }
    while (m--) {
        int t;
        cin >> t;
        auto it = st.upper_bound(t);
        if (it == st.begin()) {
            cout << "-1\n";
        } else {
            cout << *prev(it) << "\n";
            st.erase(prev(it));
        }
    }
}
 
int main() {
    ios::sync_with_stdio(0), cin.tie(0);
    solve();
}