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

#define Nmax 360
#define INF 0x3f3f3f3f
#define v first
#define e second

using namespace std;

class edge{
public:
    int x,y,capacity,cost,flow;
    edge(){
        x = y = capacity = cost = flow = 0;
    }
    edge(int a,int b,int cp,int cs,int fl){
        this->x = a;
        this->y = b;
        this->capacity = cp;
        this->cost = cs;
        this->flow = fl;
    }
};
vector<edge>E;
vector<pair<int,int> > G[Nmax];
bitset<Nmax> inQ;
queue<int> Q;
int nre = -1,N,M,S,D;
int daddy[Nmax];
int DP[Nmax];

void Insert(int a,int b,int cp,int cst,int fl)
{
    ++nre;
    E.push_back(edge(a,b,cp,cst,fl));
    G[a].push_back(make_pair(b,nre));
}

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

bool Bellman_Ford(int k)
{
    memset(DP,INF,sizeof(DP));
    DP[k] = 0;
    Q.push(k);
    while(!Q.empty())
    {
        k = Q.front();
        Q.pop();
        inQ[k] = 0;
        if(k == N)continue;

        for(vector<pair<int,int> >::iterator it = G[k].begin(); it != G[k].end(); ++it)
        if(DP[it->v] > DP[k] + E[it->e].cost && E[it->e].capacity != E[it->e].flow )
        {
            DP[it->v] = DP[k] + E[it->e].cost;
            daddy[it->v] = it->e;
            if(inQ[it->v])
                continue;
            Q.push(it->v);
            inQ[it->v] = 1;
        }
    }
    return DP[N] != INF;
}

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

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

    Read();
    FLOW(S);

    return 0;
}