#include <stdio.h>
#include <stdlib.h>

main(int argc,char ** argv)
{  FILE * fin1,* fin2,* fout;
   int v1,v2,f1,f2;
   if(argc!=4)
   {  printf("wrong number of files: %d\n",argc);
      exit(0);
   }
   fin1 = fopen(argv[1],"r");
   if(fin1==NULL)
   {  printf("can't open %d\n",argv[1]);
      exit(0);
   }
   fin2 = fopen(argv[2],"r");
   if(fin2==NULL)
   {  printf("can't open %d\n",argv[2]);
      exit(0);
   }
   fout = fopen(argv[3],"w");
   if(fout==NULL)
   {  printf("can't open %d\n",argv[3]);
      exit(0);
   }
   f1 = fscanf(fin1,"%d",&v1);
   f2 = fscanf(fin2,"%d",&v2);
   while(1)
    if(f1==EOF)
    {  while(f2!=EOF)
       {  fprintf(fout,"%d\n",v2);
          f2 = fscanf(fin2,"%d",&v2);
       }
       break;
    }
    else
    if(f2==EOF)
    {  while(f1!=EOF)
        {  fprintf(fout,"%d\n",v1);
           f1 = fscanf(fin1,"%d",&v1);
        }
        break;
    }
    else
    if(v1<v2)
    {  fprintf(fout,"%d\n",v1);
       f1 = fscanf(fin1,"%d",&v1);
    }
    else
    {  fprintf(fout,"%d\n",v2);
       f2 = fscanf(fin2,"%d",&v2);
    }
   fclose(fin1);
   fclose(fin2);
   fclose(fout);
}