worldfinal2019

#include <bits.stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    FOR(i,1,n) cin>>a[i].first;
    FOR(i,1,n) cin>>a[i].second;
    FOR(i,1,n) cin>>b[i].first;
    FOR(i,1,n) cin>>b[i].second;
    sort(a+1,a+1+n);
    sort(b+1,b+1+n);
    FOR(i,1,n) if (a[i]<b[i]) cout<<"IMPOSSIBLE";
    return;
}