using System;
using System.Linq;
int[] numbers = { 1, 2, 3, 4, 5 };
int first = numbers.First();
//first is 1
int firstEven = numbers
.First(n => n % 2 == 0);
//firstEven is 2
//int firstError = numbers
// .First(n => n > 10);//<-Error
int firstDefault = numbers
.FirstOrDefault(n => n > 10);
//lastDefault is 0
Console.WriteLine(first);
Console.WriteLine(firstEven);
Console.WriteLine(firstDefault);