#include<bits/stdc++.h>
#pragma GCC oprimize ("03")
#define FastIO ios_base::sync_with_stdio(false) , cin.tie(0) , cout.tie(0)
#define FILES freopen("fmcm.in" , "r" , stdin) , freopen("fmcm.out" , "w" , stdout)
#define pii pair < int , int >
#define pb push_back

using namespace std;

const int N = 355;

struct FMCM
{
    #define N 1005

    int n , source , sink;
    int capacity[N][N] , weight[N][N] , parent[N];
    int d[N] , nd[N];
    vector < int > G[N];
    priority_queue < int , vector < pii > , greater < pii > > s;
    queue < int > q;
    bitset < N > inq;

    inline void bellman()
    {
        int i;

        for(i = 1 ; i <= n ; i++)
            d[i] = INT_MAX;

        d[source] = 0;
        q.push(source);

        while(!q.empty())
        {
            int u = q.front();
            q.pop();
            inq[u] = 0;

            for(auto v : G[u])
            {
                if(capacity[u][v] && d[v] > d[u] + weight[u][v])
                {
                    d[v] = d[u] + weight[u][v];

                    if(inq[v])
                        continue;

                    inq[v] = 1;
                    q.push(v);
                }
            }
        }
    }

    int k = INT_MAX;
    int flow = 0;
    int minCost = 0;

    bool inline djikstra()
    {
        int i;

        for(i = 1 ; i <= n ; i++)
            nd[i] = INT_MAX;

        nd[source] = 0;
        s.push({0 , source});

        while(!s.empty())
        {
            int u = s.top().second;
            int cst = s.top().first;
            s.pop();

            if(nd[u] != cst)
                continue;

            for(auto v : G[u])
            {
                if(capacity[u][v])
                {
                    if(nd[v] > nd[u] + weight[u][v] + d[u] - d[v])
                    {
                        parent[v] = u;
                        nd[v] = nd[u] + weight[u][v] + d[u] - d[v];
                        s.push({nd[v] , v});
                    }
                }
            }
        }

        if(nd[sink] == INT_MAX)
            return 0;

        int minFlow = k - flow;
        int curr;
        int sumCost = 0;

        for(curr = sink ; curr != source ; curr = parent[curr])
            minFlow = min(minFlow , capacity[parent[curr]][curr]);

        for(curr = sink ; curr != source ; curr = parent[curr])
        {
            capacity[parent[curr]][curr] -= minFlow;
            capacity[curr][parent[curr]] += minFlow;
            sumCost += weight[parent[curr]][curr];
        }

        flow += minFlow;
        minCost += sumCost * minFlow;

        return 1;
    }

    void addEdge(int x , int y , int c , int z)
    {
         capacity[x][y] = c;

        weight[x][y] = z;
        weight[y][x] = -z;

        G[x].pb(y);
        G[y].pb(x);
    }

    int F()
    {
        bellman();
        for( ; djikstra() ; );
        return minCost;
    }
}F;


signed main()
{
	#ifndef ONLINE_JUDGE
		FastIO , FILES;
	#endif

	int n , m , source , sink;

    cin >> n >> m >> source >> sink;

    F.source = source;
    F.sink = sink;

    while(m--)
    {
        int x , y , c , z;
        cin >> x >> y >> c >> z;
        F.addEdge(x , y , c , z);
    }

    cout << F.F();
    return 0;
}