import 'dart:io'; // a little helper function that checks if the string only contains // digits and an optional minus sign at the front bool isAnInteger(String str) => str.contains(new RegExp(r'^-?\d+$')); void main() { while(true) { String input = stdin.readLineSync(); var chunks = input.split(new RegExp(r'[ ]+')); // split on 1 or more spaces if(!chunks.every(isAnInteger)) { print("not an integer!"); } else if(chunks.length > 2) { print("too many numbers!"); } else if(chunks.length < 2) { print('not enough numbers!'); } else { // parse the strings into integers var nums = chunks.map((String s) => int.parse(s)); if(nums.any((num) => num < -1000 || num > 1000)) { print("between -1000 and 1000 please!"); } else { print(nums.reduce((a, b) => a + b)); } } } }