/*Input:
14:01:57 12:47:11
13:09:42 22:16:15
08:08:06 08:38:28
23:35:07 02:49:59
14:31:45 14:46:56
*/

#include <stdio.h>

int main(int argc, char **argv)
{
    FILE *fp;
    int time1, time2, h1, m1, s1, h2, m2, s2, diff;

    fp = fopen(argv[1], "r");

    while(fscanf(fp, "%i:%i:%i %i:%i:%i\n",
        &h1, &m1, &s1, &h2, &m2, &s2) == 6)
    {

    time1 = h1*3600 + m1*60 + s1;
    time2 = h2*3600 + m2*60 + s2;

    if(time1 > time2)
    {
        diff = time1-time2;
    }
    else
    {
        diff = time2-time1;
    }

    h1 = diff/3600;
    m1 = (diff%3600)/60;
    s1 = diff%60;

    printf("%02i:%02i:%02i\n",
        h1, m1, s1);
    }

    return 0;
}