#include<stdio.h>
#include<ctype.h>
#include<math.h>
#include<malloc.h>
#include<string.h>

void concatenate(int argc, char *argv[])
{  
   FILE *fp1,*fp2;
   int i,ch;
   fp2=fopen("files.txt","a");
        for(i=1;i<argc;i++)
        {
            fp1=fopen(argv[i],"r");
            while((ch=getc(fp1))!=EOF)
            putc(ch,fp2);
        }
} 

int main(int argc, char *argv[])
{
   concatenate(argc, argv);
   return(0);
 }