program lab8txt(input, output);
 
var
  str: string;
  A: array[1..100] of integer;
  i, k: integer;
 
procedure mysearch(str: string; var k: integer);
var
  i: integer;
begin
  k := 0;
  for i := 1 to length(str)-3 do
    if (str[i] = 't') and (str[i+1] = 'h') and
       (str[i+2] = 'e') and (str[i+3] = 'n') then
      k := k + 1;
end;
 
begin
  i := 1;
  repeat
    readln(str);
    if str <> '' then 
    begin
    mysearch(str, A[i]);
    writeln('Кількість then у рядку', i, ': ', A[i]);
    i := i + 1;
  end;
  until str = '';
end.

cHJvZ3JhbSBsYWI4dHh0KGlucHV0LCBvdXRwdXQpOwoKdmFyCiAgc3RyOiBzdHJpbmc7CiAgQTogYXJyYXlbMS4uMTAwXSBvZiBpbnRlZ2VyOwogIGksIGs6IGludGVnZXI7Cgpwcm9jZWR1cmUgbXlzZWFyY2goc3RyOiBzdHJpbmc7IHZhciBrOiBpbnRlZ2VyKTsKdmFyCiAgaTogaW50ZWdlcjsKYmVnaW4KICBrIDo9IDA7CiAgZm9yIGkgOj0gMSB0byBsZW5ndGgoc3RyKS0zIGRvCiAgICBpZiAoc3RyW2ldID0gJ3QnKSBhbmQgKHN0cltpKzFdID0gJ2gnKSBhbmQKICAgICAgIChzdHJbaSsyXSA9ICdlJykgYW5kIChzdHJbaSszXSA9ICduJykgdGhlbgogICAgICBrIDo9IGsgKyAxOwplbmQ7CgpiZWdpbgogIGkgOj0gMTsKICByZXBlYXQKICAgIHJlYWRsbihzdHIpOwogICAgaWYgc3RyIDw+ICcnIHRoZW4gCiAgICBiZWdpbgogICAgbXlzZWFyY2goc3RyLCBBW2ldKTsKICAgIHdyaXRlbG4oJ9Ca0ZbQu9GM0LrRltGB0YLRjCB0aGVuINGDINGA0Y/QtNC60YMnLCBpLCAnOiAnLCBBW2ldKTsKICAgIGkgOj0gaSArIDE7CiAgZW5kOwogIHVudGlsIHN0ciA9ICcnOwplbmQu

V2Ugd2lsbCB0ZXN0IHRoaXMgY29kZSBub3csIHRoZW4gY2hlY2sgYWxsIG9wdGlvbnMsIHRoZW4gcnVuIHRoZSBzY3JpcHQgYWdhaW4sIHRoZW4gc2VlIHRoZSByZXN1bHQKV2Ugd2lsbCByZWFkIHRoZSBpbnB1dCBzdHJpbmcgZmlyc3QsIHRoZW4gc2VhcmNoIGZvciB0aGUgcGF0dGVybi4gdGhlbiwgd2UgY2FuIG91dHB1dCB0aGUgZmluYWwgY291bnQgdG8gdGhlIGNvbnNvbGUKSWYgeW91IHdhbnQgdG8gaW1wcm92ZSB5b3VyIGNvZGUsIHRoZW4geW91IHNob3VsZCB0ZXN0IGl0IGNhcmVmdWxseS4gSWYgYWxsIHRlc3RzIHBhc3MsIHRoZW4gd2UgY2FuIG1lcmdlIHRoZSBjaGFuZ2VzLg==

We will test this code now, then check all options, then run the script again, then see the result
We will read the input string first, then search for the pattern. then, we can output the final count to the console
If you want to improve your code, then you should test it carefully. If all tests pass, then we can merge the changes.