#include <fstream>
#include <string>
#include <stdio.h>
#include <vector>
#include <algorithm>
#include <math.h>
#include <set>
#include <map>
#include <string.h>
#include <queue>

#define INF 0x3f3f3f3f

using namespace std;

#ifdef DEBUG
string name = "data";
#else
string name = "fmcm";
#endif

ifstream fin(name + ".in");
ofstream fout(name + ".out");

#define MAXN 351

int n, m, s, t;

int c[MAXN][MAXN];
int f[MAXN][MAXN];
int d[MAXN][MAXN];

vector<int> g[MAXN];

int parent[MAXN];

bool inQueue[MAXN];
int dist[MAXN];

bool bellmanFord() {
    memset(inQueue, false, sizeof(inQueue));
    memset(dist, 0x3f, sizeof(dist));
    
    queue<int> q;
    
    q.push(s);
    inQueue[s] = true;
    dist[s] = 0;
    bool reachedSink = false;
    
    while (!q.empty()) {
        auto node = q.front();
        q.pop();
        inQueue[node] = false;
        
        for (auto x: g[node]) {
            bool allowsFlow = f[node][x] != c[node][x];
            
            if (allowsFlow && (dist[x] > dist[node] + d[node][x])) {
                dist[x] = dist[node] + d[node][x];
                parent[x] = node;
                
                if (!inQueue[node]) {
                    q.push(x);
                    inQueue[x] = true;
                }
                
                if (x == t) {
                    reachedSink = true;
                }
            }
        }
    }
    
    return reachedSink;
}

int main() {
    
    fin >> n >> m >> s >> t;
    
    for (int i = 0; i < m ; ++i) {
        int x, y, cc, dd;
        
        fin >> x >> y >> cc >> dd;
        
        c[x][y] = cc;
        d[x][y] = dd;
        d[y][x] = -dd;
        
        g[x].push_back(y);
        g[y].push_back(x);
    }
    
    int flow = 0;
    int cost = 0;
    
    while (bellmanFord()) {
        int minFlow = INF;
        
        int node = t;
        
        while (node != s) {
            int p = parent[node];
            
            minFlow = min(minFlow, c[p][node] - f[p][node]);
            
            node = p;
        }
        
        node = t;
        
        while (node != s) {
            int p = parent[node];
            cost += minFlow * d[p][node];
            
            f[p][node] += minFlow;
            f[node][p] -= minFlow;
            
            node = p;
        }
        
        flow += minFlow;
    }
    
    fout << cost;
    
    return 0;
}