#include <algorithm>
#include <cassert>
#include <cstdio>
#include <cstring>
#include <queue>
#include <set>
#include <vector>

using namespace std;

inline int next_int() {int d;scanf("%d", &d);return d;}

const int INF = 1e9;

int V, E;
int min_cost, max_flow;
int capacity[350][350], cost[350][350], dist[350], prev[350];
bool seen[350];
int Q[350 * 350];
vector<int> G[350];

inline void add_edge(int a, int b, int c, int d) {
	capacity[a][b] = c, cost[a][b] = +d, G[a].push_back(b);
	capacity[b][a] = 0, cost[b][a] = -d, G[b].push_back(a);
}

inline void run(const int source, const int sink) {
	while (true) {
		for (int v = 0; v < V; v++) {
			prev[v] = -1;
			seen[v] = false;
			dist[v] = INF;
		}
		int front = 0, back = 0;
		Q[back++] = source;
		dist[source] = 0;
		seen[source] = true;
		while (back - front > 0) {
			int u = Q[front++];
			for (size_t i = 0; i < G[u].size(); i++) {
				int v = G[u][i];
				if (dist[u] < INF && capacity[u][v] && dist[u] + cost[u][v] < dist[v]) {
					dist[v] = dist[u] + cost[u][v];
					prev[v] = u;
					if (!seen[v]) {
						Q[back++] = v;
						seen[v] = true;
					}
				}
			}
			seen[u] = false;
		}
		if (dist[sink] == INF) {
			break;
		}
		int path_flow = INF;
		int path_cost = dist[sink];
		for (int where = sink; where != source; where = prev[where]) {
			path_flow = min(path_flow, capacity[prev[where]][where]);
		}
		for (int where = sink; where != source; where = prev[where]) {
			capacity[prev[where]][where] -= path_flow;
			capacity[where][prev[where]] += path_flow;
		}
		min_cost += path_flow * path_cost;
		max_flow += path_flow;
	}
}

int main() {
	freopen("fmcm.in", "r", stdin);
	freopen("fmcm.out", "w", stdout);
	V = next_int();
	E = next_int();
	int source = next_int() - 1;
	int sink = next_int() - 1;
	for (int e = 0; e < E; e++) {
		int a = next_int() - 1;
		int b = next_int() - 1;
		int c = next_int();
		int d = next_int();
		add_edge(a, b, c, d);
	}
	run(source, sink);
	printf("%d\n", min_cost);
	return 0;
}