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

#define N 32

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

    FILE *p[N];
    int eofs[N];
    int i, n, done;

    if (argc < 3) {
	fprintf(stderr,"bad arg\n");
	exit(8);
    }

    n = argc - 1;
    for (i = 0; i < n; i++) {
	p[i] = fopen(argv[i+1], "r");
	if (p[i] == NULL) {
	    fprintf(stderr,"bad file: %s\n",argv[i+1]);
	    exit(8);
	}
        eofs[i] = 0;
    }

    done = 0;
    while (done != n) {
        done  = 0;
	for (i = 0; i < n; i++) {
	    if (eofs[i] == 1) {
	        done++;
	    }
	    else {
    	       if (rd_msg(p[i])) {
		    done++;
		    eofs[i] = 1;
		}
	    }
	}
    }
}

int rd_msg(FILE *in) {

    int c;

    while ((c = fgetc(in)) != EOF) {
	putchar(c);
	if (c == '\n') return 0;
    }
    return -1;
}