#include <iostream>

#include <algorithm>

#include <vector>

using namespace std;

int a[],b[];

int main(){

    int n,m;

    while(scanf("%d%d",&n,&m))

    {

        if(n ==  && m == )

            break;

        int i;

        for(i = ;i < n;i++)

            scanf("%d",&a[i]);

        for(i = ;i < m;i++)

            scanf("%d",&b[i]);

        sort(a,a + n);

        sort(b,b + m);

        vector<int> v();

        vector<int>::iterator it;

        it = set_difference(a,a + n,b,b + m,v.begin());

        v.resize(it-v.begin());

        if(v.size() == )

            cout<<"NULL"<<endl;

        else

        {

            for(it = v.begin(); it != v.end(); it++)

                cout<<*it<<" ";

            cout<<endl;

        }

    }

    return ;

}