#include <fstream>
#include <iostream>
#include <bitset>
#include <vector>
#include <queue>
#define N 370
#define INF 1000000
using namespace std;

bitset<N> viz;
vector<int> G[N];
int c[N][N],a[N][N];
int n,m,s,t;
int parent[N];
int f;
int dist[N];
int totalC=0;
void augment_path(int u, int maxEdge) {
    if (u==s) {
        f = maxEdge;
    }
    else {
        augment_path(parent[u], min(maxEdge, c[parent[u]][u]));
        c[parent[u]][u]-=f;
        c[u][parent[u]]+=f;
        totalC+=f * a[parent[u]][u];
    }
}


int main() {
    int x,y,cc,z;
    ifstream in("fmcm.in");
    ofstream out("fmcm.out");
    
    in>>n>>m>>s>>t;
    
    for(int i=0;i<m;i++) {
        in>>x>>y>>cc>>z;
        c[x][y] = cc;
        G[x].push_back(y);
        G[y].push_back(x);
        a[x][y] = z;
        a[y][x] = -z;
    }
    int mf = 0;
    while(true) {
        queue<int> q;
        bitset<1003> viz;
        viz.reset();
        
        q.push(s);
        for (int i=1;i<=n;i++) {
            dist[i] = INF;
        }
        dist[s] = 0;
        
        while (!q.empty()) {
            queue<int> nq;
            viz.reset();
            while (!q.empty()) {
                int u = q.front();q.pop();
                for (int i = 0; i<G[u].size();i++) {
                    int v = G[u][i];
                    if (c[u][v] > 0 && dist[v] > a[u][v] + dist[u]) {
                        dist[v] = a[u][v] + dist[u];
                        parent[v] = u;
                        if(!viz[v]) {
                            nq.push(v);
                            viz[v] = 1;
                        }
                    }
                }
            }
            while(!nq.empty()) {
                q.push(nq.front());
                nq.pop();
            }
        }
        
        
       if(dist[t] == INF) break;
       augment_path(t,INF);
       mf+=f;
    }
    out<<totalC;
    
    return 0;
}