#include<cstdio>
#include<cstring>
#include<queue>
#include<vector>
using namespace std;
#define MAXN 355
int N,M,S,D;
int C[MAXN][MAXN],Cst[MAXN][MAXN];
vector<int>con[MAXN];
int F,FCst;
int old_d[MAXN]; char inQ[MAXN];
queue<int> Q;
int d[MAXN],real_d[MAXN],p[MAXN];
priority_queue<pair<int,int>,vector<pair<int, int> >,greater<pair<int, int> > > H;
inline bool dijkstra()
{
    memset(d,0x3f,sizeof(d));
    d[S]=0;
    real_d[S]=0;
    H.push(make_pair(d[S],S));
    for(;!H.empty();)
    {
        int cst=H.top().first,nod=H.top().second;
        H.pop();
        if(d[nod]!=cst)
            continue;
        vector<int>::iterator it;
        for(it=con[nod].begin();it!=con[nod].end();it++)
            if (C[nod][*it])
            {
                int new_d=d[nod]+Cst[nod][*it]+old_d[nod]-old_d[*it];
                if (new_d<d[*it])
                {
                    d[*it]=new_d;
                    real_d[*it]=real_d[nod]+Cst[nod][*it];
                    p[*it]=nod;
                    H.push(make_pair(d[*it],*it));
                }
            }
    }
    memcpy(old_d,real_d,sizeof(d));
    if(d[D]==0x3f3f3f3f)
        return false;
    int Min=0x3f3f3f3f,curCst=0;
    for(int aux=D;aux!=S;aux=p[aux])
        Min=min(Min,C[p[aux]][aux]),
        curCst+=Cst[p[aux]][aux];
    F+=Min;
    FCst+=Min*real_d[D];
    for(int aux=D;aux!=S;aux=p[aux])
        C[p[aux]][aux]-=Min,
        C[aux][p[aux]]+=Min;
    return true;
}
inline bool bellmanFord()
{
    memset(old_d,0x3f,sizeof(old_d));
    old_d[S]=0;
    for(Q.push(S),inQ[S]=1;!Q.empty();Q.pop())
    {
        vector<int>::iterator it;
        int i=Q.front();
        inQ[i]=0;
        for(it=con[i].begin();it!=con[i].end();it++)
            if(C[i][*it])
            {
                if(old_d[i]+Cst[i][*it]>=old_d[*it])
                    continue;
                old_d[*it]=old_d[i]+Cst[i][*it];
                if(inQ[*it])
                    continue;
                inQ[*it]=1;
                Q.push(*it);
            }
    }
    if(old_d[D]==0x3f3f3f3f)
        return false;
    return true;
}
int main()
{
    freopen("fmcm.in", "rt", stdin);
    freopen("fmcm.out", "wt", stdout);
    scanf("%d %d %d %d",&N,&M,&S,&D);
    for(;M;M--)
    {
        int x,y;
        scanf("%d %d ",&x,&y);
        con[x].push_back(y);
        con[y].push_back(x);
        scanf("%d %d",C[x]+y,Cst[x]+y);
        Cst[y][x]=-Cst[x][y];
    }
    F=FCst=0;
    bellmanFord();
    for(;dijkstra(););
    printf("%d\n",FCst);
    return 0;
}