import Foundation

typealias Network = [String: Set<String>]

func readInput(_ filePath: String) throws -> Network {
    var map: Network = [:]
    try String(contentsOfFile: filePath, encoding: .ascii)
        .split(separator: "\n").map { $0.split(separator: "-") }
        .map { (String($0[0]), String($0[1])) }.forEach { m1, m2 in
            map[m1, default: []].insert(m2)
            map[m2, default: []].insert(m1)
        }
    return map
}

func bronkerbosch(
    _ network: Network, r: Set<String>, p: Set<String>, x: Set<String>
) -> Set<String>? {
    if p.count == 0 {
        return x.count == 0 ? r : nil
    }
    var maxClique: Set<String>? = nil
    var nextP = p
    var nextX = x
    let u = p.union(x).first!  // can also choose highest degree node
    for v in p.subtracting(network[u]!) {
        if let clique = bronkerbosch(network,
            r: r.union([v]),
            p: nextP.intersection(network[v]!),
            x: nextX.intersection(network[v]!)
        ) {
            if clique.count > (maxClique ?? []).count {
                maxClique = clique
            }
        }
        nextP.remove(v)
        nextX.insert(v)
    }
    return maxClique
}
            
let conns = try readInput(CommandLine.arguments[1])
let clique = bronkerbosch(conns, r: [], p: Set(conns.keys), x: [])
print(Array(clique ?? []).sorted().joined(separator: ","))