#include <cstdio>
#include <vector>
#include <algorithm>
#include <queue>
#include <bitset>
#include <cstring>

#define Nmax 360
#define INF 0x3f3f3f3f

using namespace std;
struct edge{
    int a,b;
    int capacity;
    int flow;
    int cost;
    edge(){
        a = b = capacity = flow = cost = 0;
    }
}E[25500];
int N,M,S,D,nr = -1;
int old_dist[Nmax];
int real_dist[Nmax];
int dist[Nmax];
int daddy[Nmax];

vector<pair<int,int> > G[Nmax];
queue<int> Q;
priority_queue<pair<int,int>,vector<pair<int,int> >,greater<pair<int,int> > > Heap;
bitset<Nmax>inQ;

void add_edge(int a,int b,int c, int z)
{
    ++nr;
    E[nr].a = a;
    E[nr].b = b;
    E[nr].capacity = c;
    E[nr].cost = z;
    G[a].push_back(make_pair(b,nr));
}

void read()
{
    scanf("%d%d%d%d",&N,&M,&S,&D);
    int a,b,c,z;
    for(int i = 1; i <= M; ++i)
    {
        scanf("%d%d%d%d",&a,&b,&c,&z);
        add_edge(a,b,c,z);
        add_edge(b,a,0,-z);
    }
}


void get_old_dist()
{
    memset(old_dist,INF,sizeof(old_dist));
    old_dist[S] = 0;
    Q.push(S);
    int k;
    while(!Q.empty())
    {
        k = Q.front(); Q.pop(); inQ[k] = 0;
        for(vector<pair<int,int> >::iterator it = G[k].begin(); it != G[k].end(); ++it)
            if(E[it->second].capacity - E[it->second].flow != 0 &&
               old_dist[it->first] > old_dist[k] + E[it->second].cost)
            {
                old_dist[it->first] = old_dist[k] + E[it->second].cost;
                if(inQ[it->first]) continue;
                inQ[it->first] = 1;
                Q.push(it->first);
            }
    }
}

bool dijkstra()
{
    memset(real_dist,INF,sizeof(real_dist));
    memset(dist,INF,sizeof(dist));

    dist[S] = real_dist[S] = 0;
    Heap.push(make_pair(0,S));
    int k,dst;
    while(!Heap.empty())
    {
        k = Heap.top().second;
        dst = Heap.top().first;
        Heap.pop();
        if(dst != dist[k]) continue;
        if(k == D) continue;
        for(vector<pair<int,int> > ::iterator it = G[k].begin(); it != G[k].end(); ++it)
            if(E[it->second].capacity - E[it->second].flow != 0 &&
               dist[it->first] > dist[k] + E[it->second].cost + old_dist[k] - old_dist[it->first])
            {
                daddy[it->first] = it->second;
                dist[it->first] = dist[k] + E[it->second].cost + old_dist[k] - old_dist[it->first];
                real_dist[it->first] = real_dist[k] + E[it->second].cost;
                Heap.push(make_pair(dist[it->first],it->first));
            }
    }
    memcpy(old_dist,real_dist,sizeof(old_dist));
    return real_dist[D] != INF;
}

void FLOW()
{
    int minFLOW,minCOST = 0;
    while(dijkstra())
    {
        if(real_dist[D] == INF) continue;
        minFLOW = INF;
        for(int nodc = D; nodc != S; nodc = E[daddy[nodc]].a + E[daddy[nodc]].b - nodc)
            minFLOW = min(minFLOW,E[daddy[nodc]].capacity - E[daddy[nodc]].flow);
        for(int nodc = D; nodc != S; nodc = E[daddy[nodc]].a + E[daddy[nodc]].b - nodc)
        {
            E[daddy[nodc]].flow += minFLOW;
            E[daddy[nodc]^1].flow -= minFLOW;
        }
        minCOST += real_dist[D] * minFLOW;
    }
    printf("%d\n",minCOST);
}

int main()
{
    freopen("fmcm.in","r",stdin);
    freopen("fmcm.out","w",stdout);

    read();
    get_old_dist();
    FLOW();

    return 0;
}