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


int main(int argc, char **argv)
{
    int i, first, noneof_count;
    FILE **fp;
    int *data, *eof;
    extern void *emalloc(unsigned size);

    /* get rid of argv[0] */
    argc--;
    argv++;

    /* allocate all storage */
    fp = (FILE **)emalloc(argc * sizeof(FILE *));
    data = (int *)emalloc(argc * sizeof(int));
    eof = (int *)emalloc(argc * sizeof(int));

    /* open files and pre-load */
    noneof_count = 0;
    for (i = 0; i < argc; i++) {
        if ((fp[i] = fopen(argv[i], "r")) == NULL) {
            perror(argv[i]);
            return 1;
        }
        eof[i] = fscanf(fp[i], "%d", &data[i]);
        if (eof[i] != EOF)
            noneof_count++;
    }

    /* merge */
    while (noneof_count) {
        /* find first number out of the non-eof files' next numbers */
        first = -1;
        for (i = 0; i < argc; i++)
            if (eof[i] != EOF && (first == -1 || data[i] < data[first]))
                first = i;

        /* output and reload */
        printf("%d\n", data[first]);
        eof[first] = fscanf(fp[first], "%d", &data[first]);
        if (eof[first] == EOF)
            noneof_count--;
    }

    return 0;
}


void *emalloc(unsigned size)
{
    void *p = malloc(size);
    if (p == NULL) {
        fprintf(stderr, "out of memory!\n");
        exit(1);
    }
    return p;
}