#include <stdio.h>

#include <glib.h>

int strcmpmatch(const char *a, const char *b)
{
    int result = 0;
    while (*a && *b) if (*a++ == *b++) result++;
    return result;
}

void stripnoncommon(char *a, const char *b)
{
    while (*a && *b) {
        if (*a++ != *b++) {
            memmove(a - 1, a, strlen(a));
            a--;
        }
    }
    *a = '\0';
}

int main()
{
    gchar *contents;
    gchar **strings;
    GError *err = NULL;

    g_file_get_contents("input", &contents, NULL, &err);
    if (err) {
        fprintf(stderr, "%s\n", err->message);
        g_error_free(err);
        return 1;
    }
    g_strstrip(contents);
    strings = g_strsplit(contents, "\n", -1);
    g_free(contents);

    int bestmatch_len = 0;
    char *bestmatch_1 = NULL;
    char *bestmatch_2 = NULL;

    for (char **first = strings; *first; first++) {
        for (char **second = strings; *second; second++) {
            if (first == second) continue;

            int len = strcmpmatch(*first, *second);
            if (len <= bestmatch_len) continue;
            bestmatch_1 = *first;
            bestmatch_2 = *second;
            bestmatch_len = len;
        }
    }

    if (!bestmatch_1 || !bestmatch_2) {
        puts("No match found!");
        goto end;
    }

    char *final = g_strdup(bestmatch_1);
    stripnoncommon(final, bestmatch_2);
    puts(final);
    g_free(final);

end:
    g_strfreev(strings);
    return 0;
}