public static void Main()
int [] numbers = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
for(int i = 0; i < numbers.Length; i++)
for(int j = i+1; j < numbers.Length; j++)
int sum = numbers[i] + numbers[j];
if(numbers.Contains(sum))
Console.WriteLine("{0} + {1} == {2}", numbers[i], numbers[j], sum);