#include <iostream>
using namespace std;

int main() {
  int n, m , k=0;
  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) {
       if(a[i]==0 and a[i+1]==0)
       cout<<i<<" "<<i+1<<endl;
    return 0;
  }
  for (int i=2 ; i<= 4*n; i+=4){
  	if(a[i]==0 and a[i+1]==0)
       cout<<i<<" "<<i+1<<endl;
    return 0;
  }
   for (int i=1 ; i<= 4*n; i+=4){
  	if(a[i]==0 and a[i+1]==0)
       cout<<i<<" "<<i+1<<endl;
    return 0;
  }
  for(int i=1; i<=4*n; i++){
  	if(a[i]==0){
  		cout<<i<<" ";
  		k++;
  	}
  }
  if(k==2) return 0;
}