#include <bits/stdc++.h>

using namespace std;
using pi = pair<int, int>;

vector<pi> G[351];
int c[351][351], dd[351], inq[351], last[351], dp[351], dp2[351];

int main() {
	ifstream cin("fmcm.in");
	ofstream cout("fmcm.out");
	int n, m, s, t, x, y, z, w;
	cin >> n >> m >> s >> t;
	while (m--) {
		cin >> x >> y >> z >> w;
		G[x].emplace_back(y, w);
		G[y].emplace_back(x, -w);
		c[x][y] = z;
	}
	int flow = 0, cost = 0;
	queue<int> Q;
	memset(dd, 0x3F, sizeof(dd));
	inq[s] = 1;
	dd[s] = 0;
	while (!Q.empty()) {
		int node = Q.front();
		Q.pop();
		inq[node] = 0;
		for (auto x : G[node])
			if (c[node][x.first] && dd[node] + x.second < dd[x.first]) {
				dd[x.first] = dd[node] + x.second;
				if (!inq[x.first]) {
					inq[x.first] = 1;
					Q.emplace(x.first);
				}
			}
	}
	//while (1) {
	//	auto comp = [&](pi a, pi b) {
	//		return a.second > b.second;
	//	};
	//	priority_queue<pi, vector<pi>, decltype(comp)> Q(comp);
	//	memset(last, 0xFF, sizeof(last));
	//	memset(dp, 0x3F, sizeof(dp));
	//	memset(dp2, 0, sizeof(dp2));
	//	Q.emplace(s, 0);
	//	dp[s] = 0;
	//	while (!Q.empty()) {
	//		int node, cost;
	//		tie(node, cost) = Q.top();
	//		Q.pop();
	//		if (dp[node] == cost)
	//			for (auto x : G[node]) {
	//				int fakecost = x.second + dd[node] - dd[x.first];
	//				if (c[node][x.first] && cost + fakecost < dp[x.first]) {
	//					last[x.first] = node;
	//					dp[x.first] = cost + fakecost;
	//					dp2[x.first] = dp2[node] + x.second;
	//					Q.emplace(x.first, cost + fakecost);
	//				}
	//			}
	//	}
	//	int curflow = INT_MAX;
	//	if (last[t] == -1)
	//		break;
	//	for (int i = t; i != s; i = last[i])
	//		curflow = min(curflow, c[last[i]][i]);
	//	for (int i = t; i != s; i = last[i]) {
	//		c[last[i]][i] -= curflow;
	//		c[i][last[i]] += curflow;
	//	}
	//	cost += dp2[t] * curflow;
	//	flow += curflow;
	//}
	//cout << cost << '\n';
}