#include <stdio.h>

void main()
{

  FILE * fin, * fout ; 
  int c ;
  unsigned char cc;
  
  fin=fopen("demo.dat","r");
  if (fin==0) { puts("demo.dat does not exist. quitting.\n"); return;}

  fout=fopen("demo.dat0","w");


  while ( (c=getc(fin)) != EOF ) 
  { 
    cc=(unsigned char) c;
    if (cc=='\n') { fputc((int) '\\', fout); fputc((int) 'n',fout); }
    else fputc(c,fout);
  }




}