using System; using System.Collections; using System.Collections.Generic; using System.Diagnostics; using System.Globalization; using System.IO; using System.Text; using System.Linq; using E = System.Linq.Enumerable; using Weight = System.Int64; using System.Threading; internal partial class Solver { public void Run() { var n = ni(); var m = ni(); var D = new PrimalDual(n); for (int i = 0; i < m; i++) { var u = ni() - 1; var v = ni() - 1; var c = ni(); var d = ni(); D.AddEdge(u, v, 1, c); D.AddEdge(u, v, 1, d); D.AddEdge(v, u, 1, c); D.AddEdge(v, u, 1, d); } cout.WriteLine(D.Run(0, n - 1, 2).TotalCost); } } public class MinCostFlowResult { public Weight TotalCost; public Weight TotalFlow; } /// /// Cost can be negative. /// O(FVE) /// public class PrimalDual { private readonly int N; private readonly List> adjacents; private readonly Weight[] _distance; private readonly bool[] _inQueue; private readonly Edge[] _prevEdges; private readonly Queue _queue; public class Edge { public int From, To; public Weight Flow, Capacity, Cost; public Edge Reverse; public Edge(int from, int to, Weight capacity, Weight cost, Weight flow = 0) { From = from; To = to; Cost = cost; Flow = flow; Capacity = capacity; } public Weight Residue { get { return Capacity - Flow; } } } public PrimalDual(int n) { N = n; adjacents = new List>(); for (int i = 0; i < n; i++) { adjacents.Add(new List()); } _distance = new Weight[N]; _inQueue = new bool[N]; _prevEdges = new Edge[N]; _queue = new Queue(N); } public IEnumerable GetEdges() { return adjacents.SelectMany(a => a); } public void AddEdge(int from, int to, Weight capacity, Weight cost) { var e = new Edge(from, to, capacity, cost); adjacents[from].Add(e); } private Edge[] FindShortestPathTree(int source) { Array.Clear(_inQueue, 0, _inQueue.Length); Array.Clear(_prevEdges, 0, _prevEdges.Length); for (int i = 0; i < N; i++) { _distance[i] = Weight.MaxValue; } _distance[source] = 0; _inQueue[source] = true; _queue.Enqueue(source); while (_queue.Count > 0) { // SPFA int now = _queue.Dequeue(); _inQueue[now] = false; foreach (var e in adjacents[now]) { if (e.Residue <= 0) { continue; } if (_distance[now] != Weight.MaxValue && _distance[e.To] > _distance[now] + e.Cost) { _distance[e.To] = _distance[now] + e.Cost; _prevEdges[e.To] = e; if (!_inQueue[e.To]) { _inQueue[e.To] = true; _queue.Enqueue(e.To); } } } } return _prevEdges; } public MinCostFlowResult Run(int source, int sink, Weight flow) { Weight totalCost = 0; Weight totalFlow = 0; while (totalFlow < flow) { var prevEdges = FindShortestPathTree(source); if (prevEdges[sink] == null) { break; } long incrementalFlow = flow - totalFlow; for (var e = prevEdges[sink]; e != null; e = prevEdges[e.From]) { incrementalFlow = Math.Min(incrementalFlow, e.Residue); } for (var e = prevEdges[sink]; e != null; e = prevEdges[e.From]) { if (e.Reverse == null) { var reverseEdge = new Edge(e.To, e.From, 0, -e.Cost) { Reverse = e }; e.Reverse = reverseEdge; adjacents[e.To].Add(reverseEdge); } totalCost += e.Cost * incrementalFlow; e.Flow += incrementalFlow; e.Reverse.Flow -= incrementalFlow; } totalFlow += incrementalFlow; } return new MinCostFlowResult { TotalCost = totalCost, TotalFlow = totalFlow }; } } // PREWRITEN CODE BEGINS FROM HERE static public class StringExtensions { static public string JoinToString(this IEnumerable source, string separator = " ") { return string.Join(separator, source); } } internal partial class Solver : Scanner { static readonly int? StackSizeInMebiByte = null; //50; public static void StartAndJoin(Action action, int maxStackSize) { var thread = new Thread(new ThreadStart(action), maxStackSize); thread.Start(); thread.Join(); } public static void Main() { #if LOCAL byte[] inputBuffer = new byte[1000000]; var inputStream = Console.OpenStandardInput(inputBuffer.Length); using (var reader = new StreamReader(inputStream, Console.InputEncoding, false, inputBuffer.Length)) { Console.SetIn(reader); new Solver(Console.In, Console.Out).Run(); } #else Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false }); if (StackSizeInMebiByte.HasValue) { StartAndJoin(() => new Solver(Console.In, Console.Out).Run(), StackSizeInMebiByte.Value * 1024 * 1024); } else { new Solver(Console.In, Console.Out).Run(); } Console.Out.Flush(); #endif } #pragma warning disable IDE0052 private readonly TextReader cin; private readonly TextWriter cout; private readonly TextWriter cerr; #pragma warning restore IDE0052 public Solver(TextReader reader, TextWriter writer) : base(reader) { cin = reader; cout = writer; cerr = Console.Error; } public Solver(string input, TextWriter writer) : this(new StringReader(input), writer) { } #pragma warning disable IDE1006 #pragma warning disable IDE0051 private int ni() { return NextInt(); } private int[] ni(int n) { return NextIntArray(n); } private long nl() { return NextLong(); } private long[] nl(int n) { return NextLongArray(n); } private double nd() { return NextDouble(); } private double[] nd(int n) { return NextDoubleArray(n); } private string ns() { return Next(); } private string[] ns(int n) { return NextArray(n); } #pragma warning restore IDE1006 #pragma warning restore IDE0051 } #if DEBUG internal static class LinqPadExtension { public static string TextDump(this T obj) { if (obj is IEnumerable) return (obj as IEnumerable).Cast().JoinToString().Dump(); else return obj.ToString().Dump(); } public static T Dump(this T obj) { return LINQPad.Extensions.Dump(obj); } } #endif public class Scanner { private readonly TextReader Reader; private readonly CultureInfo ci = CultureInfo.InvariantCulture; private readonly char[] buffer = new char[2 * 1024]; private int cursor = 0, length = 0; private string Token; private readonly StringBuilder sb = new StringBuilder(1024); public Scanner() : this(Console.In) { } public Scanner(TextReader reader) { Reader = reader; } public int NextInt() { return checked((int)NextLong()); } public long NextLong() { var s = Next(); long r = 0; int i = 0; bool negative = false; if (s[i] == '-') { negative = true; i++; } for (; i < s.Length; i++) { r = r * 10 + (s[i] - '0'); #if DEBUG if (!char.IsDigit(s[i])) throw new FormatException(); #endif } return negative ? -r : r; } public double NextDouble() { return double.Parse(Next(), ci); } public string[] NextArray(int size) { string[] array = new string[size]; for (int i = 0; i < size; i++) { array[i] = Next(); } return array; } public int[] NextIntArray(int size) { int[] array = new int[size]; for (int i = 0; i < size; i++) { array[i] = NextInt(); } return array; } public long[] NextLongArray(int size) { long[] array = new long[size]; for (int i = 0; i < size; i++) { array[i] = NextLong(); } return array; } public double[] NextDoubleArray(int size) { double[] array = new double[size]; for (int i = 0; i < size; i++) { array[i] = NextDouble(); } return array; } public string Next() { if (Token == null) { if (!StockToken()) { throw new Exception(); } } var token = Token; Token = null; return token; } public bool HasNext() { if (Token != null) { return true; } return StockToken(); } private bool StockToken() { while (true) { sb.Clear(); while (true) { if (cursor >= length) { cursor = 0; if ((length = Reader.Read(buffer, 0, buffer.Length)) <= 0) { break; } } var c = buffer[cursor++]; if (33 <= c && c <= 126) { sb.Append(c); } else { if (sb.Length > 0) break; } } if (sb.Length > 0) { Token = sb.ToString(); return true; } return false; } } }