#include <iostream>
using namespace std;
int main() {
int n, m;
cin>>n>>m;
int a[n*4+1]={0,};
for(int i=0; i<m; i++){
int x;
cin>>x;
a[x]=1;
}
for (int i = 1; i <=4*n; i+=2) {
int r = i * 4;
if (!a[r + 1] && !a[r + 2]) {
cout << r + 1 << " " << r + 2 << endl;
return 0;
}
if (!a[r + 3] && !a[r + 4]) {
cout << r + 3 << " " << r + 4 << endl;
return 0;
}
if (!a[r + 2] && !a[r + 4]) {
cout << r + 2 << " " << r + 4 << endl;
return 0;
}
}
int count = 0;
for (int i = 1; i <= n * 4; i++) {
if (!a[i]) {
cout << i << " ";
count++;
if (count == 2) break;
}
}
return 0;
}
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