Определить, сколько секунд прошло между двумя моментами времени

program upr4;
var h1,m1,s1,h2,m2,s2,r:integer;
begin
repeat
readln(h1,m1,s1);
until(h1 in [0..23])and(m1 in [0..59])and(s1 in [0..59]);
repeat
readln(h2,m2,s2);
until(h2 in [0..23])and(m2 in [0..59])and(s2 in [0..59])
and((h2>h1)or((h2=h1)and(m2>m1))or((h2=h1)and(m2=m1)and(s2>=s1)));
s2:=s2+m2*60+h2*3600;
s1:=s1+m1*60+h1*3600;
r:=s2-s1;
writeln(r);
end.

program pr1;
uses crt;
var
   h1, m1, s1: integer;
   h2, m2, s2: integer;
   countS: integer;
begin
     write('First - Enter Hours:   ');
     readln(h1);
     write('First - Enter Minutes: ');
     readln(m1);
     write('First - Enter Seconds: ');
     readln(s1);
     write('Second - Enter Hours:   ');
     readln(h2);
     write('Second - Enter Minutes: ');
     readln(m2);
     write('Second - Enter Seconds: ');
     readln(s2);
     
     countS := (s2-s1) + (m2-m1)*60 + (h2-h1)*60*60;
     
     writeln(countS);
end.

program upr4;
var h1,m1,h2,m2,r:integer;
s1,s2:longint;
begin
repeat
write('1) h m s: ');
readln(h1,m1,s1);
until(h1 in [0..23])and(m1 in [0..59])and(s1 in [0..59]);
repeat
write('2) h m s: ');
readln(h2,m2,s2);
until(h2 in [0..23])and(m2 in [0..59])and(s2 in [0..59])
and((h2>h1)or((h2=h1)and(m2>m1))or((h2=h1)and(m2=m1)and(s2>=s1)));
s2:=s2+m2*60+h2*3600;
s1:=s1+m1*60+h1*3600;
r:=s2-s1;
writeln(r);
end.