Concert_Tickets.cpp

    #include <iostream>
    #include <vector>
    #include <unistd.h>
    #include <unistd.h>
    #include <algorithm>
    #include<map>
    #include<cmath>
    #include<cstring>
    #include<sstream>
    #include <set>
    #include <unordered_set>
    #include <cstring>
    #include <string.h>
    #include <queue>
 
    using namespace std;
    #define mid(s,e)            (s+(e-s)/2)
    #define ALL(x)              (x).begin(), (x).end()
    #define endl                '\n'
    #define MAXE(vec) *max_element(ALL(vec))
    #define MINE(vec) *min_element(ALL(vec))
    #define valid(a,b,c) (a >= b && a < c ? 1 : 0)
    int dx[4] = {0,0,1,-1};
    int dy[4] = {1,-1,0,0};
    #define ll long long
    void solve()
    {
        ll n,m,nb;
				cin >> n >> m;
				map<ll,ll>mp;
				for(int i = 0; i < n;i++)
				{
					cin >> nb;
					mp[-nb]++;
				}
				for(int i = 0; i < m;i++)
				{
					cin >> nb;
					auto it = mp.lower_bound(-nb);
					if(it == mp.end())
						cout << "-1\n";
					else
					{
						cout << -it->first << endl;
						mp[it->first]--;
						if(!mp[it->first])
							mp.erase(it->first);
					}
				}

    }
    int main(void)
    {
        ll t;
        t = 1;
        while(t--)
    	    solve();
    }