import java.io.*;
class ranveer
{
public static void main(String args[])throws IOException
{
BufferedReader in =new BufferedReader(new InputStreamReader(System.in));
int m=Integer.parseInt(in.readLine());
int n=Integer.parseInt(in.readLine());
int a[]=new int [m];
int b[]=new int [n];
int c[]=new int [m+n];

for (int i=0;i<m;i++)
{
a[i]=Integer.parseInt(in.readLine());
}
for (int j=0;j>n;j++)
{
b[j]=Integer.parseInt(in.readLine());
}
for( ;i<m && j<n; )
{
 if (a[i]< b[j])
{
c[k]=a[j];
j++;
k++;
}
else if (b[j]<a[i])
{
c[k]=b[j];
j++;
k++;
}
else if (a[i]==b[j])
{
c[k]=a[i];
k++;
i++;
c[k]=b[j];
k++;
j++;
}
}
for ( ;i<m; i++)
{
c[k]=a[i];
k++;
i++;
}
for ( ;j<n;j++)
{
c[k]=b[j];
k++;
j++;
}
for (p=0;p<k;p++)
{
System.out.println(c[p]);
}
}
}