Program laba_1;

{$APPTYPE CONSOLE}
uses
   sysUtils;
var
   deg1, deg2, deg3 : real;
   IsCorrect : boolean;
begin
   writeln ('Enter a value of corners');
    repeat
       try
           IsCorrect:= TRUE;
           readln (deg1);
           if (deg1 < 0) or (deg1 > 180) then
           begin
              IsCorrect:= FALSE;
              writeln('Enter the correct value for the first corner (from 1 to 180).');
           end;
       except
          IsCorrect:= FALSE;
       writeln ('Enter the correct value');
       end

    until IsCorrect;
    repeat
       try
           IsCorrect:= TRUE;
           readln (deg2);
           if (deg2 < 0) or (deg2 > 180) then
           begin
              IsCorrect:= FALSE;
              writeln('Enter the correct value for the second corner (from 1 to 180).');
           end;
       except
             IsCorrect:= FALSE;
       writeln ('Enter the correct value');
       end

    until IsCorrect;
    repeat
        try
            IsCorrect:= TRUE;
            readln (deg3);
            if (deg3 < 0) or (deg3 > 180) then
            begin
               IsCorrect:= FALSE;
               writeln('Enter the correct value for the third corner (from 1 to 180).');
            end;
        except
             IsCorrect:= FALSE;
        writeln ('Enter the correct value');
        end

    until IsCorrect;
   if (deg1+deg2+deg3=180)  then
   begin
      if (deg1=deg2) or (deg1=deg3) or (deg2=deg3) then
        writeln ('Triangle is isosceles')
      else
        writeln ('Triangle is not isosceles');
   end
   else
    writeln ('Triangle does not exist');
    readln
end.