#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

const int INF = 1e9;
const int N = 355;

ifstream fin("fmcm.in");
ofstream fout("fmcm.out");

int n, m, source, sink, fMax, cMax;
int cap[N][N], flow[N][N], costMatrix[N][N];
vector<pair<int, int>> g[N];
vector<int> t, dist;
vector<bool> vis;

void BellmanFordCoada(int s)
{
    dist.assign(n + 1, INF);
    vector<bool> inCoada(n + 1, false);
    t.assign(n + 1, 0);
    dist[s] = 0;

    queue<int> q;
    q.push(s);
    inCoada[s] = true;
    while(!q.empty())
    {
        int x = q.front();
        q.pop();
        inCoada[x] = false;

        for(auto neigh : g[x])
        {
            int y = neigh.first;
            int cost = neigh.second;

            if(flow[x][y] < cap[x][y] && dist[x] + cost < dist[y])
            {
                dist[y] = dist[x] + cost;
                t[y] = x;
                if(!inCoada[y])
                {
                    q.push(y);
                    inCoada[y] = true;
                }
            }
        }
    }
}

void computeNonNegativeGraph()
{
    BellmanFordCoada(source);

    for(int i = 1; i <= n; i++)
    {
        for(auto& vec : g[i])
            vec.second = vec.second + dist[i] - dist[vec.first];
    }
}

void Dijkstra(int s)
{
    dist.assign(n + 1, INF);
    vis.assign(n + 1, false);
    t.assign(n + 1, 0);
    priority_queue<pair<int, int>> heap;

    dist[s] = 0;
    heap.push({0, s});
 
    int costTotal = 0;
    while(!heap.empty())
    {
        int nod = heap.top().second;
        int cost = -heap.top().first;
        heap.pop();
 
        if(vis[nod])
            continue;
 
        vis[nod] = true;
 
        for(auto &y : g[nod])
            if(!vis[y.first] && flow[nod][y.first] != cap[nod][y.first] && cost + y.second < dist[y.first])
            {
                heap.push({-(cost + y.second), y.first});
                dist[y.first] = cost + y.second;
                t[y.first] = nod;
            }
    }
}

int maxFlowMinCost()
{
    fMax = 0;
    cMax = 0;
    do
    {
        Dijkstra(source);

        if(dist[sink] == INF)
            break;

        int fmin = 1 << 30;
        int realDistance = 0;
        for(int node = sink; node != source; node = t[node])
        {
            fmin = min(fmin, cap[t[node]][node] - flow[t[node]][node]);
            realDistance += costMatrix[t[node]][node];
        }

        if(fmin == 0)
            continue;

        fMax += fmin;
        cMax += realDistance * fmin;
        for(int node = sink; node != source; node = t[node])
        {
            flow[t[node]][node] += fmin;
            flow[node][t[node]] -= fmin;
        }
    } while(dist[sink] != INF);

    return cMax;
}

int main()
{
    fin >> n >> m >> source >> sink;
    for(int i = 0; i < m; i++)
    {
        int x, y, c, cost;
        fin >> x >> y >> c >> cost;
        g[x].push_back({y, cost});
        g[y].push_back({x, -cost});
        cap[x][y] = c;
        costMatrix[x][y] = cost;
        costMatrix[y][x] = -cost;
    }

    computeNonNegativeGraph();

    fout << maxFlowMinCost() << '\n';

    return 0;
}