#include <bits/stdc++.h>
//#pragma GCC optimize("Ofast")
 
using namespace std;
ifstream f("fmcm.in");
ofstream g("fmcm.out");
#define cin f
#define cout g
//#define int long long
const int Max = 351;
void nos()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
}
//https://cp-algorithms.com/graph/min_cost_flow.html
struct Edge{
		int from, to ,capacity,cost;};
	vector < vector < int > > graph;
	int cost[Max][Max];
	int capacity[Max][Max];
	int d[Max];
	int p[Max];
	bitset < Max > inq;
	const int INF = 1e9;
	void Shortest_paths(int n, int v0)
	{
		//bellman ford
		int i;
		for(i=1;i<=n;i++)
			d[i] = INF,p[i] = -1;
		d[v0] = 0;
		inq.reset();
		queue < int > q;
		q.push(v0);
		while(!q.empty())
		{
			int nod = q.front();
			q.pop();
			inq[nod] = false;
			for(auto vec : graph[nod])
				if(capacity[nod][vec] > 0  and d[vec] > d[nod] + cost[nod][vec])
					{
						d[vec] = d[nod] + cost[nod][vec];
						p[vec] = nod;
						if(!inq[vec])
						{
							inq[vec] = true;
							q.push(vec);
						}
					}
		}
	}
	
	pair < int , int > MCMF_cost(int n,vector < Edge > edges,int s, int t)
	{
		graph.assign(n + 1,vector<int>());
		for(auto e : edges)
		{	
			graph[e.from].push_back(e.to);
      	  	graph[e.to].push_back(e.from);
        	cost[e.from][e.to] = e.cost;
        	cost[e.to][e.from] = -e.cost;
        	capacity[e.from][e.to] = e.capacity;
		}
	int flow = 0;
	int cost = 0;
	while(true)
	{
		//cout<<"actualizez un picut \n";
		Shortest_paths(n + 1,s);
		if(d[t] == INF)
			break;
		int thisflow = INF;
		int current = t;
		while(current != s)
		{
			thisflow = min(thisflow,capacity[p[current]][current]);
			current = p[current];
		}
		//am cam terminat 
		flow += thisflow;
		cost += thisflow * d[t];
		current = t;
		while(current != s)
		{
			capacity[p[current]][current] -= thisflow;
            capacity[current][p[current]] += thisflow;
            current = p[current];
		}
		//actualizez muchiile alese
	}
	return {flow,cost};
	}
 
int n,m,source,sink;
vector < Edge > muchii;
void read()
{
	f>>n>>m>>source>>sink;
	int i;
	for(i=1;i<=m;i++)
	{
		int from,to,cap,cost;
		f>>from>>to>>cap>>cost;
		muchii.push_back({from,to,cap,cost});
	}
}
void solve()
{
    //MCMF flow_graph;
    cout<<MCMF_cost(n,muchii,source,sink).second;
}
void restart()
{
 
}
int32_t main()
{
   //nos();
 
        read();
        solve();
        restart();
    
    return 0;
}