#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#define DIM 20
int main(int argc, char **argv)
{
	if(argc!=2)
	{
		fprintf(stderr,"wrong number of arguments\n");
		return EXIT_FAILURE;
	}
	int n,i,temp;
	time_t t;
	n=atoi(argv[1]);
	char *str1={"F1.txt"};
	char *str2={"F2.txt"};
	FILE *fp1,*fp2;
	if(((fp1=fopen(str1,"w"))==NULL)||((fp2=fopen(str2,"w"))==NULL))
	{
		fprintf(stderr,"unable to open files\n");
		return EXIT_FAILURE;
	}
	srand((unsigned) time(&t));
	for(i=0;i<n;i++)
	{
		temp=rand()%100000;
		fprintf(fp1,"%d\n",temp);
	}

	for(i=0;i<n;i++)
	{
		temp=rand()%100000;
		fprintf(fp2,"%d\n",temp);
	}
	fclose(fp1);
	fclose(fp2);
	char str3[DIM];
	sprintf(str3,"sort -n -o ./%s ./%s",str1,str1);
	printf("%s\n",str3);
	system(str3);
	sprintf(str3,"sort -n -o ./%s ./%s ",str2,str2);
	printf("%s\n",str3);
	system(str3);
	if(((fp1=fopen(str1,"r"))==NULL)||((fp2=fopen(str2,"r"))==NULL))
	{
		fprintf(stderr,"unable to open files\n");
		return EXIT_FAILURE;
	}
	strcpy(str1,"F1.bin");
	strcpy(str2,"F2.bin");
	FILE *fp3,*fp4;
	if(((fp3=fopen(str1,"wb"))==NULL)||((fp4=fopen(str2,"wb"))==NULL))
	{
		fprintf(stderr,"unable to open files\n");
		return EXIT_FAILURE;
	}

	while(fscanf(fp1,"%d",&i)!=EOF)
	{
		fwrite(&i,sizeof(int),1,fp3);
	}

	while(fscanf(fp2,"%d",&i)!=EOF)
	{
		fwrite(&i,sizeof(int),1,fp4);
	}
	fclose(fp1);
	fclose(fp2);
	fclose(fp3);
	fclose(fp4);
	if((fp1=fopen("F12.sorted","w+b"))==NULL)
	{
		fprintf(stderr,"unable to open files\n");
		return EXIT_FAILURE;
	}
	if(((fp3=fopen(str1,"r+b"))==NULL)||((fp4=fopen(str2,"r+b"))==NULL))
	{
		fprintf(stderr,"unable to open files\n");
		return EXIT_FAILURE;
	}

	int j=0,h1,h2;
	i=0;
	fread(&h1,sizeof(int),1,fp3);
	fread(&h2,sizeof(int),1,fp4);
	while((i<n)&&(j<n))
	{
		if(h1>h2)
		{
			fwrite(&h2,sizeof(int),1,fp1);
			i++;
			if(i<n)
				fread(&h2,sizeof(int),1,fp4);
		}
		else
		{
			fwrite(&h1,sizeof(int),1,fp1);
			j++;
			if(j<n)
				fread(&h1,sizeof(int),1,fp3);

		}
	}
	while(i<n)
	{
		fwrite(&h2,sizeof(int),1,fp1);
		i++;
		if(i<n)
			fread(&h2,sizeof(int),1,fp4);
	}
	while(j<n)
	{
		fwrite(&h1,sizeof(int),1,fp1);
		j++;
		if(j<n)
			fread(&h1,sizeof(int),1,fp3);
	}
	fclose(fp1);
	fclose(fp3);
	fclose(fp4);
	return EXIT_SUCCESS;
}