1 #include<stdio.h>
 2 #include<string.h>
 3 int main()
 4 {
 5     int test,aa,bb,cc,xx,yy,zz;
 6     int st,en;
 7     scanf("%d",&test);
 8     while(test--)
 9     {
10         scanf("%d:%d:%d %d:%d:%d",&aa,&bb,&cc,&xx,&yy,&zz);
11         st=aa*3600+bb*60+cc;
12         en=(xx%12)*3600+yy*60+zz;
13         int ans=st-en;
14         if(ans<0) ans+=43200;
15         aa=ans/3600;
16         bb=((ans%3600)/60)%60;
17         cc=ans%60 ;
18         printf("%02d:%02d:%02d\n",aa,bb,cc);
19     }
20     return 0;
21 }