<RuntimeDirectory>\System.configuration.dll <RuntimeDirectory>\System.Security.dll System.Configuration var input = File.ReadAllLines(Path.Combine(Path.GetDirectoryName(Util.CurrentQueryPath), "..", "day1.txt")).Select(int.Parse).ToList(); var part1 = input.Select(mass => (mass/3)-2).Sum(); part1.Dump(); int additionalFuel(int mass) { var f = (mass/3)-2; return f > 0 ? f + additionalFuel(f) : 0; } var part2 = input.Select(additionalFuel).Sum(); part2.Dump();