#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 52100, INF = (1ll << 31) + 10;
int head[N], to[N], ne[N], w[N], idx;
int dep[N], cur[N];
void add(int u, int v, int x)
{
	//正向边 偶数 
	to[idx] = v, ne[idx] = head[u], w[idx] = x, head[u] = idx++;
	//反向边 奇数
	to[idx] = u, ne[idx] = head[v], w[idx] = 0, head[v] = idx++; 
}
bool bfs(int s, int t)
{
	memset(dep, 0, sizeof dep);
	queue<int> q;
	q.push(s);
	dep[s] = 1;
	while(q.size())
	{
		int u = q.front();
		q.pop();
		for(int i = head[u]; i != -1; i = ne[i])
		{
			int v = to[i];
			if(w[i] && !dep[v])//如果有剩余容量且未被访问 
			{
				dep[v] = dep[u] + 1;
				q.push(v);
			}
		}
	}
	return dep[t];
}
int dfs(int u, int t, int flow)
{
	if(u == t) return flow;
	int res = 0;
	for(int &i = cur[u]; i != -1 && flow; i = ne[i])
	{
		int v = to[i];
		if(w[i] && dep[v] == dep[u] + 1)
		{
			int f = dfs(v, t, min(flow, w[i]));
			
			w[i] -= f;
			w[i ^ 1] += f;
			
			flow -= f;
			res += f; 
			
			if(!flow) break;
		}
	}
	return res;
}
int dinic(int s, int t)
{
	int maxflow = 0;
	while(bfs(s, t))//建立分层图 
	{
		memcpy(cur, head, sizeof head);
		while (int flow = dfs(s, t, INF))
		{
			maxflow += flow;//寻找增广路 
		}
	} 
	return maxflow;
}
signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	memset(head, -1, sizeof head);
	int n, m, s, t;
	cin >> n >> m >> s >> t;
	for(int i = 1; i <= m; i++)
	{
		int u, v, w;
		cin >> u >> v >> w;
		add(u, v, w);
	}
	cout << dinic(s, t);
	return 0;
}