#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

ifstream fin("fmcm.in");
ofstream fout("fmcm.out");

const int N = 355, INF = 1e9;

int n, m, source, sink;
int flowMax, costMin;
int t[N], flow[N][N], cap[N][N], cost[N][N];
vector<int> g[N], realDist, positiveDist, newRealDist;
vector<bool> vis;

void BellmanFord()
{
	vector<bool> inCoada(n + 1, false);
	realDist.assign(n + 1, INF);

	queue<int> coada;
	coada.push(source);
	inCoada[source] = true;
	realDist[source] = 0;
	t[source] = 0;

	while (!coada.empty())
	{
		int x = coada.front();
		coada.pop();

		inCoada[x] = false;

		for (int y : g[x])
		{
			if (realDist[x] + cost[x][y] < realDist[y] && flow[x][y] != cap[x][y])
			{
				t[y] = x;
				realDist[y] = realDist[x] + cost[x][y];
				if (!inCoada[y])
				{
					coada.push(y);
					inCoada[y] = true;
				}
			}
		}
	}
}

void Dijkstra()
{
	positiveDist.assign(n + 1, INF);
	newRealDist.assign(n + 1, INF);
	vis.assign(n + 1, false);

	priority_queue<pair<int, int>> heap;
	heap.push({ 0, source });

	positiveDist[source] = newRealDist[source] = 0;

	while (!heap.empty())
	{
		int x = heap.top().second;
		heap.pop();

		if (vis[x])
			continue;

		vis[x] = true;

		for (int y : g[x])
		{
			int positiveCostXY = realDist[x] + cost[x][y] - realDist[y];

			if (!vis[y] && flow[x][y] != cap[x][y] && positiveDist[x] + positiveCostXY < positiveDist[y])
			{
				positiveDist[y] = positiveDist[x] + positiveCostXY;
				heap.push({ -positiveDist[y], y });
				newRealDist[y] = newRealDist[x] + cost[x][y];
				t[y] = x;
			}
		}
	}

	realDist = newRealDist;
}

void maxFlowMinCost()
{
	BellmanFord();

	while (true)
	{
		Dijkstra();

		if (positiveDist[sink] == INF)
			break;

		int flowMin = 1 << 30;
		for (int node = sink; node != source; node = t[node])
			flowMin = min(flowMin, cap[t[node]][node] - flow[t[node]][node]);

		flowMax += flowMin;
		costMin += realDist[sink] * flowMin;
		for (int node = sink; node != source; node = t[node])
		{
			flow[t[node]][node] += flowMin;
			flow[node][t[node]] -= flowMin;
		}
	}
}

int main()
{
	fin >> n >> m >> source >> sink;

	for (int i = 0; i < m; i++)
	{
		int x, y, c, price;
		fin >> x >> y >> c >> price;

		g[x].push_back(y);
		g[y].push_back(x);
		cap[x][y] = c;
		cost[x][y] = price;
		cost[y][x] = -price;
	}

	maxFlowMinCost();
	fout << costMin;
	return 0;
}