#include <fstream>
#include <cstdlib>
#include <cstring>
#include <queue>

using namespace std;

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

const int N = 353;

int n, s, d;

int best[N];
int viz[N];
int fat[N];

int f[N][N];
int c[N][N];
int cost[N][N];

void read() {
	int m;
	in >> n >> m >> s >> d;

	while (m--) {
		int a, b, cap, cst;
		in >> a >> b >> cap >> cst;

		c[a][b] = cap;
		cost[a][b] = cst;
		cost[b][a] = -cst;
	}
}

bool road() {
	queue <int> q;
	memset(best, 0x3f3f3f3f, sizeof(best));
	memset(viz, 0, sizeof(viz));
	q.push(s);
	best[s] = 0;
	viz[s] = 1;

	while (!q.empty()) {
		int node = q.front();

		for (int next = 1; next <= n; ++next)
			if (c[node][next] - f[node][next] > 0 && best[node] + cost[node][next] < best[next]) {
				++viz[next];
				if (viz[next] == n)
					return viz[d];

				fat[next] = node;
				best[next] = best[node] + cost[node][next];

				q.push(next);
			}

		q.pop();
	}

	return viz[d];
}

long long solve() {
	long long res = 0;

	while (road()) {
		int node = d;
		int minFlow = 0x3f3f3f3f;

		while (node != s) {
			if (c[fat[node]][node] - f[fat[node]][node] < minFlow)
				minFlow = c[fat[node]][node] - f[fat[node]][node];

			node = fat[node];
		}

		node = d;

		while (node != s) {
			f[fat[node]][node] += minFlow;
			f[node][fat[node]] -= minFlow;

			res += minFlow * cost[fat[node]][node];

			node = fat[node];
		}
	}

	return res;
}

int main() {
	read();
	out << solve() << "\n";

	return 0;
}