type
time=array [1..3] of byte;
var
a,b:time;
c,d:string[8];
e,f:int64;
Procedure Strong(var c:string[8]; var a:time);
var
x:byte;
y:integer;
Begin
For x:=1 to 2 do
Begin
Val(Copy(c,1,Pos(':',c)-1),a[x],y);
Delete(c,1,Pos(':',c));
End;
Val(c,a[3],y);
End;
Begin
ReadLn(c);
Strong(c,a);
ReadLn(d);
Strong(d,b);
e:=(b[1]*3600+b[2]*60+b[3])-(a[1]*3600+a[2]*60+a[3]);
If e<0 then e:=e+24*3600;
If e div 3600<10 then Write('0',e div 3600,':')
else Write(e div 3600,':');
e:=e mod 3600;
If e div 60<10 then Write('0',e div 60,':')
else Write(e div 60,':');
If e mod 60<10 then Write('0',e mod 60)
else Write(e mod 60);
End.