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

#define TRUE 1
#define FALSE 0

int main(int argc, char **argv) {

    char buf1[1024];
    char buf2[1024];
    int n, fd1, fd2, index1 = 0, index2 = 0;

    if (argc != 3) {
	exit(EXIT_FAILURE);
    }
    
    fd1 = open(argv[1], O_RDONLY);
    if (fd1 < 0) {
	exit(EXIT_FAILURE);
    }
    
    fd2 = open(argv[2], O_RDONLY);
    if (fd2 < 0) {
	exit(EXIT_FAILURE);
    }
    
    while(TRUE) {
	index1 = 0;
	index2 = 0;
	
	memset(buf1, 0, 1024);
	memset(buf2, 0, 1024);
		
	while (n = (read(fd1, &buf1[index1], 1)) > 0) {
	    if (buf1[index1] == '\n') {
		break;
	    }
	    index1++;
	}
	if (n == 0) {
	    break;
	}
	
	while (n = (read(fd2, &buf2[index2], 1)) > 0) {
	    if (buf2[index2] == '\n') {
		break;
	    }
	    index2++;
	}
	if (n == 0) {
	    break;
	}
	
	if (index1 == index2) {
	    printf("%s", buf1);
	}
    }
}