import std.stdio, std.conv, std.string, std.array, std.range, std.algorithm, std.container;
import std.math, std.random, std.bigint, std.datetime, std.format;
void main(string[] args){ if(args.length > 1) if(args[1] == "-debug") DEBUG = 1; solve(); } bool DEBUG = 0; 
void log(A ...)(lazy A a){ if(DEBUG) print(a); }
void print(){ writeln(""); } void print(T)(T t){ writeln(t); } void print(T, A ...)(T t, A a){ write(t, " "), print(a); }
string unsplit(T)(T xs){ return xs.array.to!(string[]).join(" "); }
string scan(){ static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res; }
T scan(T)(){ return scan.to!T; } T[] scan(T)(int n){ return n.iota.map!(i => scan!T()).array; }
T lowerTo(T)(ref T x, T y){ if(x > y) x = y; return x; } T raiseTo(T)(ref T x, T y){ if(x < y) x = y; return x; }

// ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- //

void solve(){
  int n = scan!int;
  int m = scan!int;
  int[] as = scan!int(m);
  
  int[] odds, evens;
  foreach(a; as) if(a % 2) odds ~= a; else evens ~= a;
  
  if(n == 1 || odds.length > 2){
    "Impossible".writeln;
    return;
  }
  
  int[] ans, bns;
  if(odds.length == 0){
    ans = evens;
    foreach(a; evens) bns ~= a;
    bns[0] -= 1;
    bns ~= 1;
  }
  else if(odds.length == 1){
    if(odds[0] == 1){
      ans = [1] ~ evens;
      bns = evens ~ 1;
    }
    else{
      ans = odds ~ evens;
      bns = [odds[0] - 1] ~ evens ~ 1;
    }
  }
  else if(odds.length == 2){
    if(odds[0] == 1){
      ans = [1] ~ evens ~ odds[1];
      bns = evens ~ (odds[1] + 1);
    }
    else{
      ans = [odds[0]] ~ evens ~ odds[1];
      bns = [odds[0] - 1] ~ evens ~ (odds[1] + 1);
    }
  }
  
  print(ans.unsplit);
  print(bns.length);
  print(bns.unsplit);
}