#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<int> g[N];
vector<int> t, realDist, newRealDist, positiveDist;
vector<bool> vis;

void BellmanFordCoada(int s)
{
    vector<bool> inCoada(n + 1, false);
    queue<int> q;
    realDist.assign(n + 1, INF);
    t.assign(n + 1, 0);

    q.push(s);
    inCoada[s] = true;
    realDist[s] = 0;
    while(!q.empty())
    {
        int x = q.front();
        q.pop();
        inCoada[x] = false;

        for(int y : g[x])
        {
            int cost = costMatrix[x][y];

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

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

    positiveDist[s] = newRealDist[s] = 0;
    heap.push({0, s});
 
    while(!heap.empty())
    {
        int x = heap.top().second;
        int cost = -heap.top().first;
        heap.pop();
 
        if(vis[x])
            continue;
 
        vis[x] = true;
 
        for(int y : g[x])
        {
            int positiveCost = realDist[x] + costMatrix[x][y] - realDist[y];
            if(!vis[y] && flow[x][y] != cap[x][y] && positiveDist[x] + positiveCost < positiveDist[y])
            {
                heap.push({-(positiveDist[x] + positiveCost), y});
                positiveDist[y] = positiveDist[x] + positiveCost;
                newRealDist[y] = newRealDist[x] + costMatrix[x][y];
                t[y] = x;
            }
        }
    }

    realDist = newRealDist;
}

int maxFlowMinCost()
{  
    // for computing initial distances
    BellmanFordCoada(source);

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

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

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

        if(fmin == 0)
            continue;

        fMax += fmin;
        cMax += realDist[sink] * fmin;
        for(int node = sink; node != source; node = t[node])
        {
            flow[t[node]][node] += fmin;
            flow[node][t[node]] -= fmin;
        }
    } while(realDist[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);
        g[y].push_back(x);
        cap[x][y] = c;
        costMatrix[x][y] = cost;
        costMatrix[y][x] = -cost;
    }

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

    return 0;
}