Встречено 'until', а ожидалось ';' - PascalABC.NET

program calculator; //v1.1
 
var
  a, b, rez: real;oper, calc: string;flag_start: boolean;
 
begin
  flag_start := false;
  calc := 'N';
  rez := 0;
  repeat
    if(flag_start = false) then
    begin
      writeln('Are you want to use calculator:Y/N/');
      readln(calc);
      if(calc <> 'Y') then break;
      writeln('Please input the first number');
      readln(a);
      writeln('please choose operator:+,-,*,/,div,mod');
      readln(oper);
      rez := a;
      writeln('Please input a second number');
      readln(a);
      case oper of
        '+': rez := rez + a;
        '-': rez := rez - a;
        '*': rez := rez * a;
        '/': rez := rez / a;
        'div': rez := int(round(rez) div round(a));
        'mod': rez := int(round(rez) mod round(a));
      else writeln( 'You chose wrong operator');
      end;
    end
    else
    begin
      writeln('please choose operator:+,-,*,/,div,mod');
      readln(oper);
      rez := a;
      writeln('Please input a second number');
      readln(a);
      case oper of
        '+': rez := rez + a;
        '-': rez := rez - a;
        '*': rez := rez * a;
        '/': rez := rez / a;
        'div': rez := int(round(rez) div round(a));
        'mod': rez := int(round(rez) mod round(a));
      else writeln( 'You chose wrong operator');
      end;
    end; // <--- Этого не хватало
    writeln('Will you continue to use a calculator?Y/N');
    readln(calc);
  until(calc = 'N');
  WriteLn('Result is', rez:8:2);
  readln;
end.