else if (cur.isDecimalDigit()) {
                        // Number: [0-9]{1,3}(.[0-9]{3})*
                        String val = "";

                        //get number
                        do {
                            val += (cur.cp() == '.') ? "." : cur.cp() - '0';
                            cur.incPosition();
                        }
                        while (cur.isDecimalDigit() || cur.cp() == '.');

                        //check dot position
                        for (int i = val.length() - 1, c = 0; i >= 0; i--, c++) {
                            /*
                            . && c!=3 err
                            . && c==3 c=0
                            d && c==3 err
                            d && c!=3 ok
                             */
                            if (val.charAt(i) == '.' && c == 3) {
                                c = -1; // c++ = 0

                            } else if (c == 3 || val.charAt(i) == '.') {
                                compiler.addMessage(
                                        true,
                                        start,
                                        "wrong position of delimiters in number");
                                break;

                            }

                        }
                        //remove not num chars
                        val = val.replaceAll("\\D", "");

                        //calculate value of number
                        long num = 0;

                        try {
                            for (char c: val.toCharArray()) {
                                num = Math.addExact(Math.multiplyExact(num, 10), (c - '0'));
                            }
                        } catch (ArithmeticException e) {

                            compiler.addMessage(
                                    true,
                                    start,
                                    "integral constant is too large");
                        }
                        val = "" + num;

                        //add dots
                        String res = "";
                        for (int i = val.length() - 1, c = 0; i >= 0; i--, c++) {
                            if (c == 3) {
                                c = 0;
                                res = "." + res;
                            }
                            res = val.charAt(i) + res;
                        }
                        val = res;

                        if (cur.isLetter()) {
                            compiler.addMessage(
                                    true,
                                    new Position(cur),
                                    "delimiter required");
                        }
                        return new NumberToken(
                                val,
                                start,
                                new Position(cur));
                    }