using System;
using System.Linq;
(int first, int last) GetFirstLast(int[] ar) {
var first = -1;
var last = -1;
if (ar.Any()) {
first = ar[0];
last = ar[^1];
}
return (first, last);
}
var ar = new[] {2, 3, 5};
var result = GetFirstLast(ar);
//result.first is 2
//result.last is 5
Console.WriteLine($"first is {result.first}");
Console.WriteLine($"last is {result.last}");