#pragma GCC optimize(3,"Ofast","inline")
#include<bits/stdc++.h>
#define ll long long
using namespace std;
const int inf = INT_MAX;
const ll INF = (0x3f3f3f3f3f3f3f3fll);
const int maxn = 1.2e3 + 5;
struct HLPP
{
	struct Edge
	{
		int v, rev;
		ll cap;
	};
	int n, sp, tp, lim, ht, lcnt;
	ll exf[maxn];
	vector<Edge> G[maxn];
	vector<int> hq[maxn], gap[maxn], h, sum;
	void init(int nn, int s, int t)
	{
		sp = s, tp = t, n = nn, lim = n + 1, ht = lcnt = 0;
		for(int i = 1; i <= n; ++ i) G[i].clear(), exf[i] = 0;
	}
	void add_edge(int u, int v, ll cap)
	{
		G[u].push_back( {v, int(G[v].size()) , cap});
		G[v].push_back( {u, int(G[u].size()) - 1, 0});
	}
	void update(int u, int nh)
	{
		++lcnt;
		if(h[u] != lim) --sum[h[u]];
		h[u] = nh;
		if(nh == lim) return;
		++sum[ht = nh];
		gap[nh].push_back(u);
		if(exf[u] > 0) hq[nh].push_back(u);
	}
	void relabel()
	{
		queue<int> q;
		for(int i = 0; i <= lim; ++ i) hq[i].clear(), gap[i].clear();
		h.assign(lim, lim), sum.assign(lim, 0), q.push(tp);
		lcnt = ht = h[tp] = 0;
		while(!q.empty())
		{
			int u = q.front();
			q.pop();
			for(Edge &e : G[u]) if(h[e.v] == lim && G[e.v][e.rev].cap) update(e.v, h[u] + 1), q.push(e.v);
			ht = h[u];
		}
	}
	void push(int u, Edge &e)
	{
		if(!exf[e.v]) hq[h[e.v]].push_back(e.v);
		ll df = min(exf[u], e.cap);
		e.cap -= df, G[e.v][e.rev].cap += df;
		exf[u] -= df, exf[e.v] += df;
	}
	void discharge(int u)
	{
		int nh = lim;
		if(h[u] == lim) return;
		for(Edge &e : G[u])
		{
			if(!e.cap) continue;
			if(h[u] == h[e.v] + 1)
			{
				push(u, e);
				if(exf[u] <= 0) return;
			}
			else if(nh > h[e.v] + 1) nh = h[e.v] + 1;
		}
		if(sum[h[u]] > 1) update(u, nh);
		else
		{
			for( ; ht >= h[u]; gap[ht--].clear())
			for(int &i : gap[ht]) update(i, lim);
		}
	}
	ll hlpp()
	{
		exf[sp] = INF, exf[tp] = -INF, relabel();
		for(Edge &e : G[sp]) push(sp, e);
		for( ; ~ht; --ht)
		{
			while(!hq[ht].empty())
			{
				int u = hq[ht].back();
				hq[ht].pop_back();
				discharge(u);
				if(lcnt > (n << 2)) relabel();
			}
		}
		return exf[tp] + INF;
	}
}hp;
signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(0) , cout.tie(0);
	int n, m, s, t, u, v, w;
	cin >> n >> m >> s >> t;
	hp.init(n, s, t);
	while(m --)
	{
		cin >> u >> v >> w;
		hp.add_edge(u, v, w);
	}
	cout << hp.hlpp() << '\n';
	return 0;
}