#include <bits/stdc++.h>
#define N 400
#define INF 0x3f3f3f3f
using namespace std;
ifstream fin("fmcm.in");
ofstream fout("fmcm.out");
struct muchie
{
    int x,y,c,z;
};
vector<int>g[N];
int capacity[N][N],cost[N][N];
bool viz[N];
int n,m,s,t,maxFlow;
long long minCost;
int d[N],dp[N],D[N],tata[N];
queue<int>q;
void BellmanFord()
{
    d[s]=0;
    q.push(s);
    viz[s]=1;
    while(!q.empty())
    {
        int nod=q.front();
        q.pop();
        viz[nod]=0;
        for(auto x:g[nod])
            if(capacity[nod][x] && d[x]>d[nod]+cost[nod][x])
        {
            d[x]=d[nod]+cost[nod][x];
            if(!viz[x]) viz[x]=1,q.push(x);
        }
    }
}
struct myqueue
{
    int nod,cost;
    bool operator < (const myqueue x) const
    {
        return x.cost<cost;
    }
};
priority_queue<myqueue>pq;
bool Dijkstra()
{
    memset(dp,INF,sizeof(dp));
    dp[s]=D[s]=0;
    pq.push({s,0});
    while(!pq.empty())
    {
        int nod=pq.top().nod;
        int z=pq.top().cost;
        pq.pop();
        if(z!=dp[nod]) continue;
        for(auto x:g[nod])
        {
            if(!capacity[nod][x]) continue;
            int newCost=z+cost[nod][x]+d[nod]-d[x];
            if(newCost<dp[x])
            {
                dp[x]=newCost;
                D[x]=D[nod]+cost[nod][x];
                tata[x]=nod;
                if(x!=t) pq.push({x,newCost});
            }
        }
    }
    if(dp[t]==INF) return 0;
    int minFlow=INF;
    for(int x=t;x!=s;x=tata[x])
    {
        minFlow=min(minFlow,capacity[tata[x]][x]);
        if(!minFlow) return 0;
    }
    maxFlow+=minFlow;
    minCost+=1ll*minFlow*D[t];
    for(int x=t;x!=s;x=tata[x])
        capacity[tata[x]][x]-=minFlow,
        capacity[x][tata[x]]+=minFlow;
    return 1;
}
pair<int,int>FMCM()
{
    BellmanFord();
    while(Dijkstra());
    return {maxFlow,minCost};
}
int main()
{
    int i,x,y,c,z;
    fin>>n>>m>>s>>t;
    while(m--)
        fin>>x>>y>>c>>z,
        g[x].push_back(y),
        g[y].push_back(x),
        capacity[x][y]+=c,
        cost[x][y]=z,
        cost[y][x]=-z;
    fout<<FMCM().second;
    return 0;
}