Solution to my Codingame challenge in Dart

solution.dart

import 'dart:io';

String readLineSync() {
  String? s = stdin.readLineSync();
  return s == null ? '' : s;
}

class Change with Comparable<Change> {
  int line;
  int column;
  String addition;

  Change({
    required this.line,
    required this.column,
    required String addition,
  }) : addition = addition.replaceAll("\\n", "\n");

  @override
  int compareTo(Change other) {
    return line == other.line ? column - other.column : line - other.line;
  }

  String applyToString(String string) {
    List<String> lines = string.split("\n");
    lines[line] = lines[line].substring(0, column) + addition + lines[line].substring(column);
    return lines.join("\n");
  }

  @override
  String toString() {
    return "{line: $line, column: $column, addition: $addition}";
  }
}

void main() {
  String string = readLineSync().replaceAll("\\n", "\n");;
  int changeCount = int.parse(readLineSync());
  List<Change> changes = [];
  for (int i = 0; i < changeCount; i++) {
      String rawChange = readLineSync();
      final split = rawChange.split("|");
      changes.add(Change(
        line: int.parse(split[0]),
        column: int.parse(split[1]),
        addition: split[2],
      ));
  }

  changes.sort((a, b) => a.compareTo(b));
  changes = changes.reversed.toList();


  changes.forEach((change) {
    string = change.applyToString(string);
  });

  print(string);
}