using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Runtime.CompilerServices;
using System.Text;
using static Template;
using static System.Console;
using static System.Convert;
using static System.Math;
using Pi = Pair<int, int>;
using Number = System.Int64;

class Solver
{
    Scanner sc = new Scanner();
    //
    int N, M, s, t;
    int[][] dist;
    MaxFlow f;
    public void Solve()
    {
        sc.Make(out N, out M, out s, out t);
        s--;t--;
        var ms = sc.ArrInt2D(M);
        dist = Create(N, () => Create(N, () => int.MaxValue / 2));
        for (var i = 0; i < N; i++)
            dist[i][i] = 0;
        foreach (var m in ms)
        {
            m[0]--;m[1]--;
            dist[m[0]][m[1]] = m[2];

        }
        for (var k = 0; k < N; k++)
            for (var i = 0; i < N; i++)
                for (var j = 0; j < N; j++)
                    chmin(ref dist[i][j], dist[i][k] + dist[k][j]);
        f = new MaxFlow(N);
        foreach (var m in ms)
        {
            int from = m[0], to = m[1], c = m[2], d = m[3];
            if (dist[s][from] + c + dist[to][t] == dist[s][t])
                f.AddDirectedEdge(from, to, d);
        }
        WriteLine(f.Execute(s, t));
    }
}

public class MaxFlow
{
    readonly List<Edge>[] G;
    readonly int[] lv, iter;

    public MaxFlow(int V)
    {
        G = new List<Edge>[V];
        lv = new int[V];
        iter = new int[V];
        for (int i = 0; i < G.Length; i++)
            G[i] = new List<Edge>();
    }

    public void AddDirectedEdge(int from, int to, int cap)
        => addEdge(from, to, cap, 0);

    public void AddUndirectedEdge(int from, int to, int cap)
        => addEdge(from, to, cap, cap);

    void addEdge(int f, int t, int c1, int c2)
    {
        var a = new Edge(t, c1);
        var b = new Edge(f, c2);
        Edge.Link(a, b);
        G[f].Add(a);
        G[t].Add(b);
    }

    public int Execute(int src, int sink, int f = -1)
    {
        int flow = 0;
        if (f < 0) f = int.MaxValue;
        while (f > 0)
        {
            bfs(src);
            if (lv[sink] == 0) return flow;
            Array.Clear(iter, 0, iter.Length);
            int df;
            while ((df = dfs(src, sink, f)) > 0) { flow += df; f -= df; }
        }
        return flow;
    }

    void bfs(int s)
    {
        Array.Clear(lv, 0, lv.Length);
        var q = new Queue<int>();
        lv[s] = 1;
        q.Enqueue(s);
        while (q.Count > 0)
        {
            var v = q.Dequeue();
            foreach (var e in G[v])
                if (e.Cap > 0 && lv[e.To] == 0)
                {
                    lv[e.To] = lv[v] + 1;
                    q.Enqueue(e.To);
                }
        }

    }
    int dfs(int v, int t, int f)
    {
        if (v == t) return f;
        int ret = 0;
        for (; iter[v] < G[v].Count; iter[v]++)
        {
            var e = G[v][iter[v]];
            if (e.Cap <= 0 || lv[v] >= lv[e.To]) continue;
            int df = dfs(e.To, t, Math.Min(f, e.Cap));
            if (df <= 0) continue;
            e.Cap -= df;
            e.Rev.Cap += df;
            ret += df; f -= df;
            if (f == 0) break;
        }
        return ret;

    }
    class Edge
    {
        public static void Link(Edge e1, Edge e2)
        {
            e1.Rev = e2; e2.Rev = e1;
        }
        public int To { get; private set; }
        public Edge Rev { get; private set; }
        public int Cap { get; set; }
        public Edge(int t, int c)
        {
            To = t;
            Cap = c;
        }
        public override string ToString()
        {
            return string.Format("to: {0}, cap: {1}", To, Cap);
        }
    }
}
#region Template
public class Template
{
    static void Main(string[] args)
    {
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        new Solver().Solve();
        Console.Out.Flush();
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmin<T>(ref T num, T val) where T : IComparable<T>
    { if (num.CompareTo(val) == 1) { num = val; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmax<T>(ref T num, T val) where T : IComparable<T>
    { if (num.CompareTo(val) == -1) { num = val; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void swap<T>(ref T v1, ref T v2)
    { var t = v2; v2 = v1; v1 = t; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static T[] Create<T>(int n, Func<T> f)
    {
        var rt = new T[n];
        for (var i = 0; i < rt.Length; ++i)
            rt[i] = f();
        return rt;
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static T[] Create<T>(int n, Func<int, T> f)
    {
        var rt = new T[n];
        for (var i = 0; i < rt.Length; ++i)
            rt[i] = f(i);
        return rt;
    }
    public static void Fail<T>(T s) { Console.WriteLine(s); Console.Out.Close(); Environment.Exit(0); }
}

public class Scanner
{
    StreamReader sr;
    public Scanner() { sr = new StreamReader(Console.OpenStandardInput()); }
    public Scanner(string path) { sr = new StreamReader(path); }
    public string Str => sr.ReadLine().Trim();
    public int Int => int.Parse(Str);
    public long Long => long.Parse(Str);
    public double Double => double.Parse(Str);
    public int[] ArrInt => Str.Split(' ').Select(int.Parse).ToArray();
    public long[] ArrLong => Str.Split(' ').Select(long.Parse).ToArray();
    public char[][] Grid(int n) => Create(n, () => Str.ToCharArray());
    public int[] ArrInt1D(int n) => Create(n, () => Int);
    public long[] ArrLong1D(int n) => Create(n, () => Long);
    public int[][] ArrInt2D(int n) => Create(n, () => ArrInt);
    public long[][] ArrLong2D(int n) => Create(n, () => ArrLong);
    public Pair<T1, T2> PairMake<T1, T2>() => new Pair<T1, T2>(Next<T1>(), Next<T2>());
    public Pair<T1, T2, T3> PairMake<T1, T2, T3>() => new Pair<T1, T2, T3>(Next<T1>(), Next<T2>(), Next<T3>());
    private Queue<string> q = new Queue<string>();
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public T Next<T>()
    {
        if (q.Count == 0)
            foreach (var item in Str.Split(' ')) q.Enqueue(item);
        return (T)Convert.ChangeType(q.Dequeue(), typeof(T));
    }
    public void Make<T1>(out T1 v1) => v1 = Next<T1>();
    public void Make<T1, T2>(out T1 v1, out T2 v2)
    { v1 = Next<T1>();  v2 = Next<T2>(); }
    public void Make<T1, T2, T3>(out T1 v1, out T2 v2, out T3 v3)
    { Make(out v1, out v2); v3 = Next<T3>();}
    public void Make<T1, T2, T3, T4>(out T1 v1, out T2 v2, out T3 v3, out T4 v4)
    { Make(out v1, out v2, out v3); v4 = Next<T4>();}
    public void Make<T1, T2, T3, T4, T5>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5)
    { Make(out v1, out v2, out v3, out v4); v5 = Next<T5>();}
    public void Make<T1, T2, T3, T4, T5, T6>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5, out T6 v6)
    { Make(out v1, out v2, out v3, out v4, out v5); v6 = Next<T6>();}
}
public class Pair<T1, T2> : IComparable<Pair<T1, T2>>
{
    public T1 v1;
    public T2 v2;
    public Pair() { }
    public Pair(T1 v1, T2 v2)
    { this.v1 = v1; this.v2 = v2; }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public int CompareTo(Pair<T1, T2> p)
    {
        var c = Comparer<T1>.Default.Compare(v1, p.v1);
        if (c == 0)
            c = Comparer<T2>.Default.Compare(v2, p.v2);
        return c;
    }
    public override string ToString()
        => $"{v1.ToString()} {v2.ToString()}";
    public void Deconstruct(out T1 a, out T2 b) { a = v1; b = v2; }
}

public class Pair<T1, T2, T3> : Pair<T1, T2>, IComparable<Pair<T1, T2, T3>>
{
    public T3 v3;
    public Pair() : base() { }
    public Pair(T1 v1, T2 v2, T3 v3) : base(v1, v2)
    { this.v3 = v3; }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public int CompareTo(Pair<T1, T2, T3> p)
    {
        var c = base.CompareTo(p);
        if (c == 0)
            c = Comparer<T3>.Default.Compare(v3, p.v3);
        return c;
    }
    public override string ToString()
        => $"{base.ToString()} {v3.ToString()}";
    public void Deconstruct(out T1 a, out T2 b,out T3 c) { Deconstruct(out a, out b);c = v3; }
}
#endregion



Measured memory_bytes: 18916